From 2e7607371222ea5361f12d0b19a052e4b2099571 Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Fri, 7 Jun 2019 15:08:05 +0300
Subject: [PATCH 1/5] Initial work on distributions

---
 .../kotlin/scientifik/kmath/chains/Chain.kt   | 32 +++++------
 .../kmath/{ => coroutines}/CoroutinesExtra.kt | 17 +++---
 .../scientifik/kmath/streaming/BufferFlow.kt  |  4 +-
 .../scientifik/kmath/chains/ChainExt.kt       |  2 +-
 .../kmath/structures/LazyNDStructure.kt       |  2 +-
 .../kmath/streaming/BufferFlowTest.kt         |  6 +--
 kmath-prob/build.gradle.kts                   |  3 +-
 .../scientifik/kmath/prob/Distribution.kt     | 28 ++++++++++
 .../scientifik/kmath/prob/RandomGenerator.kt  | 11 ++++
 .../kmath/prob/CommonDistributions.kt         | 53 +++++++++++++++++++
 .../prob/CommonsRandomProviderWrapper.kt      | 18 +++++++
 11 files changed, 144 insertions(+), 32 deletions(-)
 rename kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/{ => coroutines}/CoroutinesExtra.kt (90%)
 create mode 100644 kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt
 create mode 100644 kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt
 create mode 100644 kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt
 create mode 100644 kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt

diff --git a/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/chains/Chain.kt b/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/chains/Chain.kt
index 4d2f604e1..4adc2a9a7 100644
--- a/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/chains/Chain.kt
+++ b/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/chains/Chain.kt
@@ -18,6 +18,7 @@ package scientifik.kmath.chains
 
 import kotlinx.atomicfu.atomic
 import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.flow.Flow
 
 
 /**
@@ -28,7 +29,7 @@ interface Chain<out R> {
     /**
      * Last cached value of the chain. Returns null if [next] was not called
      */
-    val value: R?
+    fun peek(): R?
 
     /**
      * Generate next value, changing state if needed
@@ -46,13 +47,12 @@ interface Chain<out R> {
  * Chain as a coroutine flow. The flow emit affects chain state and vice versa
  */
 @FlowPreview
-val <R> Chain<R>.flow
+val <R> Chain<R>.flow: Flow<R>
     get() = kotlinx.coroutines.flow.flow { while (true) emit(next()) }
 
 fun <T> Iterator<T>.asChain(): Chain<T> = SimpleChain { next() }
 fun <T> Sequence<T>.asChain(): Chain<T> = iterator().asChain()
 
-
 /**
  * Map the chain result using suspended transformation. Initial chain result can no longer be safely consumed
  * since mapped chain consumes tokens. Accepts regular transformation function
@@ -60,7 +60,7 @@ fun <T> Sequence<T>.asChain(): Chain<T> = iterator().asChain()
 fun <T, R> Chain<T>.map(func: (T) -> R): Chain<R> {
     val parent = this;
     return object : Chain<R> {
-        override val value: R? get() = parent.value?.let(func)
+        override fun peek(): R? = parent.peek()?.let(func)
 
         override suspend fun next(): R {
             return func(parent.next())
@@ -77,7 +77,7 @@ fun <T, R> Chain<T>.map(func: (T) -> R): Chain<R> {
  */
 class SimpleChain<out R>(private val gen: suspend () -> R) : Chain<R> {
     private val atomicValue = atomic<R?>(null)
-    override val value: R? get() = atomicValue.value
+    override fun peek(): R? = atomicValue.value
 
     override suspend fun next(): R = gen().also { atomicValue.lazySet(it) }
 
@@ -95,16 +95,16 @@ class MarkovChain<out R : Any>(private val seed: () -> R, private val gen: suspe
     constructor(seed: R, gen: suspend (R) -> R) : this({ seed }, gen)
 
     private val atomicValue = atomic<R?>(null)
-    override val value: R get() = atomicValue.value ?: seed()
+    override fun peek(): R = atomicValue.value ?: seed()
 
     override suspend fun next(): R {
-        val newValue = gen(value)
+        val newValue = gen(peek())
         atomicValue.lazySet(newValue)
-        return value
+        return peek()
     }
 
     override fun fork(): Chain<R> {
-        return MarkovChain(value, gen)
+        return MarkovChain(peek(), gen)
     }
 }
 
@@ -121,12 +121,12 @@ class StatefulChain<S, out R>(
     constructor(state: S, seed: R, gen: suspend S.(R) -> R) : this(state, { seed }, gen)
 
     private val atomicValue = atomic<R?>(null)
-    override val value: R get() = atomicValue.value ?: seed(state)
+    override fun peek(): R = atomicValue.value ?: seed(state)
 
     override suspend fun next(): R {
-        val newValue = gen(state, value)
+        val newValue = gen(state, peek())
         atomicValue.lazySet(newValue)
-        return value
+        return peek()
     }
 
     override fun fork(): Chain<R> {
@@ -137,10 +137,10 @@ class StatefulChain<S, out R>(
 /**
  * A chain that repeats the same value
  */
-class ConstantChain<out T>(override val value: T) : Chain<T> {
-    override suspend fun next(): T {
-        return value
-    }
+class ConstantChain<out T>(val value: T) : Chain<T> {
+    override fun peek(): T? = value
+
+    override suspend fun next(): T = value
 
     override fun fork(): Chain<T> {
         return this
diff --git a/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/CoroutinesExtra.kt b/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/coroutines/CoroutinesExtra.kt
similarity index 90%
rename from kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/CoroutinesExtra.kt
rename to kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/coroutines/CoroutinesExtra.kt
index 51cc07511..dc82d1881 100644
--- a/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/CoroutinesExtra.kt
+++ b/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/coroutines/CoroutinesExtra.kt
@@ -1,4 +1,4 @@
-package scientifik.kmath
+package scientifik.kmath.coroutines
 
 import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.produce
@@ -42,13 +42,14 @@ fun <T, R> Flow<T>.async(
 }
 
 @FlowPreview
-fun <T, R> AsyncFlow<T>.map(action: (T) -> R) = AsyncFlow(deferredFlow.map { input ->
-    //TODO add function composition
-    LazyDeferred(input.dispatcher) {
-        input.start(this)
-        action(input.await())
-    }
-})
+fun <T, R> AsyncFlow<T>.map(action: (T) -> R) =
+    AsyncFlow(deferredFlow.map { input ->
+        //TODO add function composition
+        LazyDeferred(input.dispatcher) {
+            input.start(this)
+            action(input.await())
+        }
+    })
 
 @ExperimentalCoroutinesApi
 @FlowPreview
diff --git a/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/streaming/BufferFlow.kt b/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/streaming/BufferFlow.kt
index d5e94fc3b..85ce73c4b 100644
--- a/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/streaming/BufferFlow.kt
+++ b/kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/streaming/BufferFlow.kt
@@ -22,7 +22,7 @@ fun <T> Flow<Buffer<out T>>.spread(): Flow<T> = flatMapConcat { it.asFlow() }
  * Collect incoming flow into fixed size chunks
  */
 @FlowPreview
-fun <T> Flow<T>.chunked(bufferSize: Int, bufferFactory: BufferFactory<T>) = flow {
+fun <T> Flow<T>.chunked(bufferSize: Int, bufferFactory: BufferFactory<T>): Flow<Buffer<T>> = flow {
     require(bufferSize > 0) { "Resulting chunk size must be more than zero" }
     val list = ArrayList<T>(bufferSize)
     var counter = 0
@@ -46,7 +46,7 @@ fun <T> Flow<T>.chunked(bufferSize: Int, bufferFactory: BufferFactory<T>) = flow
  * Specialized flow chunker for real buffer
  */
 @FlowPreview
-fun Flow<Double>.chunked(bufferSize: Int) = flow {
+fun Flow<Double>.chunked(bufferSize: Int): Flow<DoubleBuffer> = flow {
     require(bufferSize > 0) { "Resulting chunk size must be more than zero" }
     val array = DoubleArray(bufferSize)
     var counter = 0
diff --git a/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/chains/ChainExt.kt b/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/chains/ChainExt.kt
index 4f2c4cb8b..b634c5ae2 100644
--- a/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/chains/ChainExt.kt
+++ b/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/chains/ChainExt.kt
@@ -27,7 +27,7 @@ fun <R> Chain<R>.asSequence(): Sequence<R> = object : Sequence<R> {
 fun <T, R> Chain<T>.map(func: suspend (T) -> R): Chain<R> {
     val parent = this;
     return object : Chain<R> {
-        override val value: R? get() = runBlocking { parent.value?.let { func(it) } }
+        override fun peek(): R? = runBlocking { parent.peek()?.let { func(it) } }
 
         override suspend fun next(): R {
             return func(parent.next())
diff --git a/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/structures/LazyNDStructure.kt b/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/structures/LazyNDStructure.kt
index fa81fc67b..784b7cd10 100644
--- a/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/structures/LazyNDStructure.kt
+++ b/kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/structures/LazyNDStructure.kt
@@ -1,7 +1,7 @@
 package scientifik.kmath.structures
 
 import kotlinx.coroutines.*
-import scientifik.kmath.Math
+import scientifik.kmath.coroutines.Math
 
 class LazyNDStructure<T>(
     val scope: CoroutineScope,
diff --git a/kmath-coroutines/src/jvmTest/kotlin/scientifik/kmath/streaming/BufferFlowTest.kt b/kmath-coroutines/src/jvmTest/kotlin/scientifik/kmath/streaming/BufferFlowTest.kt
index 5b65c2120..4fd397993 100644
--- a/kmath-coroutines/src/jvmTest/kotlin/scientifik/kmath/streaming/BufferFlowTest.kt
+++ b/kmath-coroutines/src/jvmTest/kotlin/scientifik/kmath/streaming/BufferFlowTest.kt
@@ -4,9 +4,9 @@ import kotlinx.coroutines.*
 import kotlinx.coroutines.flow.asFlow
 import kotlinx.coroutines.flow.collect
 import org.junit.Test
-import scientifik.kmath.async
-import scientifik.kmath.collect
-import scientifik.kmath.map
+import scientifik.kmath.coroutines.async
+import scientifik.kmath.coroutines.collect
+import scientifik.kmath.coroutines.map
 import java.util.concurrent.Executors
 
 
diff --git a/kmath-prob/build.gradle.kts b/kmath-prob/build.gradle.kts
index 28ab2d6c7..77a4aefc8 100644
--- a/kmath-prob/build.gradle.kts
+++ b/kmath-prob/build.gradle.kts
@@ -6,13 +6,14 @@ plugins {
 kotlin.sourceSets {
     commonMain {
         dependencies {
-            api(project(":kmath-core"))
             api(project(":kmath-coroutines"))
             compileOnly("org.jetbrains.kotlinx:atomicfu-common:${Versions.atomicfuVersion}")
         }
     }
     jvmMain {
         dependencies {
+            // https://mvnrepository.com/artifact/org.apache.commons/commons-rng-simple
+            api("org.apache.commons:commons-rng-sampling:1.2")
             compileOnly("org.jetbrains.kotlinx:atomicfu:${Versions.atomicfuVersion}")
         }
     }
diff --git a/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt
new file mode 100644
index 000000000..946b173ff
--- /dev/null
+++ b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt
@@ -0,0 +1,28 @@
+package scientifik.kmath.prob
+
+import scientifik.kmath.chains.Chain
+
+/**
+ * A distribution of typed objects
+ */
+interface Distribution<T : Any> {
+    /**
+     * A probability value for given argument [arg].
+     * For continuous distributions returns PDF
+     */
+    fun probability(arg: T): Double
+
+    /**
+     * Create a chain of samples from this distribution.
+     * The chain is not guaranteed to be stateless.
+     */
+    fun sample(generator: RandomGenerator): Chain<T>
+    //TODO add sample bunch generator
+}
+
+interface UnivariateDistribution<T : Comparable<T>> : Distribution<T> {
+    /**
+     * Cumulative distribution for ordered parameter
+     */
+    fun cumulative(arg: T): Double
+}
\ No newline at end of file
diff --git a/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt
new file mode 100644
index 000000000..89cbc615c
--- /dev/null
+++ b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt
@@ -0,0 +1,11 @@
+package scientifik.kmath.prob
+
+/**
+ * A basic generator
+ */
+interface RandomGenerator {
+    fun nextDouble(): Double
+    fun nextInt(): Int
+    fun nextLong(): Long
+    fun nextBlock(size: Int): ByteArray
+}
\ No newline at end of file
diff --git a/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt b/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt
new file mode 100644
index 000000000..c08008c28
--- /dev/null
+++ b/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt
@@ -0,0 +1,53 @@
+package scientifik.kmath.prob
+
+import org.apache.commons.rng.sampling.distribution.*
+import scientifik.kmath.chains.Chain
+import scientifik.kmath.chains.SimpleChain
+import kotlin.math.PI
+import kotlin.math.exp
+import kotlin.math.sqrt
+
+class NormalDistribution(val mean: Double, val sigma: Double) : UnivariateDistribution<Double> {
+    enum class Sampler {
+        BoxMuller,
+        Marsaglia,
+        Ziggurat
+    }
+
+    override fun probability(arg: Double): Double {
+        val d = (arg - mean) / sigma
+        return 1.0 / sqrt(2.0 * PI * sigma) * exp(-d * d / 2)
+    }
+
+    override fun cumulative(arg: Double): Double {
+        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
+    }
+
+    fun sample(generator: RandomGenerator, sampler: Sampler): Chain<Double> {
+        val normalized = when (sampler) {
+            Sampler.BoxMuller -> BoxMullerNormalizedGaussianSampler(generator.asProvider())
+            Sampler.Marsaglia -> MarsagliaNormalizedGaussianSampler(generator.asProvider())
+            Sampler.Ziggurat -> ZigguratNormalizedGaussianSampler(generator.asProvider())
+        }
+        val gauss = GaussianSampler(normalized, mean, sigma)
+        //TODO add generator to chain state to allow stateful forks
+        return SimpleChain { gauss.sample() }
+    }
+
+    override fun sample(generator: RandomGenerator): Chain<Double> = sample(generator, Sampler.BoxMuller)
+}
+
+class PoissonDistribution(val mean: Double): UnivariateDistribution<Int>{
+    override fun probability(arg: Int): Double {
+        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
+    }
+
+    override fun cumulative(arg: Int): Double {
+        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
+    }
+
+    override fun sample(generator: RandomGenerator): Chain<Int> {
+        val sampler = PoissonSampler(generator.asProvider(), mean)
+        return SimpleChain{sampler.sample()}
+    }
+}
\ No newline at end of file
diff --git a/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt b/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt
new file mode 100644
index 000000000..ad408460d
--- /dev/null
+++ b/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt
@@ -0,0 +1,18 @@
+package scientifik.kmath.prob
+
+import org.apache.commons.rng.UniformRandomProvider
+
+inline class CommonsRandomProviderWrapper(val provider: UniformRandomProvider) : RandomGenerator {
+    override fun nextDouble(): Double = provider.nextDouble()
+
+    override fun nextInt(): Int = provider.nextInt()
+
+    override fun nextLong(): Long = provider.nextLong()
+
+    override fun nextBlock(size: Int): ByteArray = ByteArray(size).also { provider.nextBytes(it) }
+}
+
+fun UniformRandomProvider.asGenerator(): RandomGenerator = CommonsRandomProviderWrapper(this)
+
+fun RandomGenerator.asProvider(): UniformRandomProvider =
+    (this as? CommonsRandomProviderWrapper)?.provider ?: TODO("implement reverse wrapper")
\ No newline at end of file

From 9c2164cd6496f173633854719794fbb58387902c Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Sat, 8 Jun 2019 14:26:44 +0300
Subject: [PATCH 2/5] Distribution implementations for commons-math

---
 {benchmarks => examples}/build.gradle         |  0
 .../kmath/structures/ArrayBenchmark.kt        |  0
 .../kmath/structures/BufferBenchmark.kt       |  0
 .../kmath/structures/NDFieldBenchmark.kt      |  0
 .../kmath/linear/LinearAlgebraBenchmark.kt    |  3 +
 .../kmath/linear/MultiplicationBenchmark.kt   |  2 +
 .../kmath/structures/ComplexNDBenchmark.kt    |  0
 .../kmath/structures/NDFieldBenchmark.kt      |  0
 .../structures/StructureReadBenchmark.kt      |  0
 .../structures/StructureWriteBenchmark.kt     |  0
 kmath-commons/build.gradle.kts                |  1 +
 .../expressions/DiffExpression.kt             | 30 +++++--
 .../kmath/{ => commons}/linear/CMMatrix.kt    | 18 ++--
 .../kmath/{ => commons}/linear/CMSolver.kt    |  3 +-
 .../commons/prob/CMRandomGeneratorWrapper.kt  | 18 ++++
 .../kmath/commons/prob/CommonsDistribution.kt | 84 +++++++++++++++++++
 .../transform/Transformations.kt              |  2 +-
 .../{ => commons}/expressions/AutoDiffTest.kt |  5 +-
 kmath-prob/build.gradle.kts                   |  2 +-
 .../scientifik/kmath/prob/Distribution.kt     |  9 +-
 .../scientifik/kmath/prob/RandomChain.kt      | 17 ++++
 .../kmath/prob/CommonDistributions.kt         | 53 ------------
 .../prob/CommonsRandomProviderWrapper.kt      | 18 ----
 settings.gradle.kts                           |  2 +-
 24 files changed, 174 insertions(+), 93 deletions(-)
 rename {benchmarks => examples}/build.gradle (100%)
 rename {benchmarks => examples}/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt (100%)
 rename {benchmarks => examples}/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt (100%)
 rename {benchmarks => examples}/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt (100%)
 rename {benchmarks => examples}/src/main/kotlin/scientifik/kmath/linear/LinearAlgebraBenchmark.kt (92%)
 rename {benchmarks => examples}/src/main/kotlin/scientifik/kmath/linear/MultiplicationBenchmark.kt (92%)
 rename {benchmarks => examples}/src/main/kotlin/scientifik/kmath/structures/ComplexNDBenchmark.kt (100%)
 rename {benchmarks => examples}/src/main/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt (100%)
 rename {benchmarks => examples}/src/main/kotlin/scientifik/kmath/structures/StructureReadBenchmark.kt (100%)
 rename {benchmarks => examples}/src/main/kotlin/scientifik/kmath/structures/StructureWriteBenchmark.kt (100%)
 rename kmath-commons/src/main/kotlin/scientifik/kmath/{ => commons}/expressions/DiffExpression.kt (83%)
 rename kmath-commons/src/main/kotlin/scientifik/kmath/{ => commons}/linear/CMMatrix.kt (83%)
 rename kmath-commons/src/main/kotlin/scientifik/kmath/{ => commons}/linear/CMSolver.kt (94%)
 create mode 100644 kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt
 create mode 100644 kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt
 rename kmath-commons/src/main/kotlin/scientifik/kmath/{ => commons}/transform/Transformations.kt (97%)
 rename kmath-commons/src/test/kotlin/scientifik/kmath/{ => commons}/expressions/AutoDiffTest.kt (78%)
 create mode 100644 kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomChain.kt
 delete mode 100644 kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt
 delete mode 100644 kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt

diff --git a/benchmarks/build.gradle b/examples/build.gradle
similarity index 100%
rename from benchmarks/build.gradle
rename to examples/build.gradle
diff --git a/benchmarks/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt b/examples/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
similarity index 100%
rename from benchmarks/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
rename to examples/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
diff --git a/benchmarks/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt b/examples/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
similarity index 100%
rename from benchmarks/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
rename to examples/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
diff --git a/benchmarks/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt b/examples/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
similarity index 100%
rename from benchmarks/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
rename to examples/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
diff --git a/benchmarks/src/main/kotlin/scientifik/kmath/linear/LinearAlgebraBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/linear/LinearAlgebraBenchmark.kt
similarity index 92%
rename from benchmarks/src/main/kotlin/scientifik/kmath/linear/LinearAlgebraBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/linear/LinearAlgebraBenchmark.kt
index c397e9bd0..960f03de3 100644
--- a/benchmarks/src/main/kotlin/scientifik/kmath/linear/LinearAlgebraBenchmark.kt
+++ b/examples/src/main/kotlin/scientifik/kmath/linear/LinearAlgebraBenchmark.kt
@@ -1,6 +1,9 @@
 package scientifik.kmath.linear
 
 import koma.matrix.ejml.EJMLMatrixFactory
+import scientifik.kmath.commons.linear.CMMatrixContext
+import scientifik.kmath.commons.linear.inverse
+import scientifik.kmath.commons.linear.toCM
 import scientifik.kmath.operations.RealField
 import scientifik.kmath.structures.Matrix
 import kotlin.contracts.ExperimentalContracts
diff --git a/benchmarks/src/main/kotlin/scientifik/kmath/linear/MultiplicationBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/linear/MultiplicationBenchmark.kt
similarity index 92%
rename from benchmarks/src/main/kotlin/scientifik/kmath/linear/MultiplicationBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/linear/MultiplicationBenchmark.kt
index 31a890867..03bd0001c 100644
--- a/benchmarks/src/main/kotlin/scientifik/kmath/linear/MultiplicationBenchmark.kt
+++ b/examples/src/main/kotlin/scientifik/kmath/linear/MultiplicationBenchmark.kt
@@ -1,6 +1,8 @@
 package scientifik.kmath.linear
 
 import koma.matrix.ejml.EJMLMatrixFactory
+import scientifik.kmath.commons.linear.CMMatrixContext
+import scientifik.kmath.commons.linear.toCM
 import scientifik.kmath.operations.RealField
 import scientifik.kmath.structures.Matrix
 import kotlin.random.Random
diff --git a/benchmarks/src/main/kotlin/scientifik/kmath/structures/ComplexNDBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/structures/ComplexNDBenchmark.kt
similarity index 100%
rename from benchmarks/src/main/kotlin/scientifik/kmath/structures/ComplexNDBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/structures/ComplexNDBenchmark.kt
diff --git a/benchmarks/src/main/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
similarity index 100%
rename from benchmarks/src/main/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
diff --git a/benchmarks/src/main/kotlin/scientifik/kmath/structures/StructureReadBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/structures/StructureReadBenchmark.kt
similarity index 100%
rename from benchmarks/src/main/kotlin/scientifik/kmath/structures/StructureReadBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/structures/StructureReadBenchmark.kt
diff --git a/benchmarks/src/main/kotlin/scientifik/kmath/structures/StructureWriteBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/structures/StructureWriteBenchmark.kt
similarity index 100%
rename from benchmarks/src/main/kotlin/scientifik/kmath/structures/StructureWriteBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/structures/StructureWriteBenchmark.kt
diff --git a/kmath-commons/build.gradle.kts b/kmath-commons/build.gradle.kts
index c610749be..ffdc27d43 100644
--- a/kmath-commons/build.gradle.kts
+++ b/kmath-commons/build.gradle.kts
@@ -8,6 +8,7 @@ description = "Commons math binding for kmath"
 dependencies {
     api(project(":kmath-core"))
     api(project(":kmath-coroutines"))
+    api(project(":kmath-prob"))
     api("org.apache.commons:commons-math3:3.6.1")
     testImplementation("org.jetbrains.kotlin:kotlin-test")
     testImplementation("org.jetbrains.kotlin:kotlin-test-junit")
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/expressions/DiffExpression.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/expressions/DiffExpression.kt
similarity index 83%
rename from kmath-commons/src/main/kotlin/scientifik/kmath/expressions/DiffExpression.kt
rename to kmath-commons/src/main/kotlin/scientifik/kmath/commons/expressions/DiffExpression.kt
index 5f6d0d8fe..e687cb2af 100644
--- a/kmath-commons/src/main/kotlin/scientifik/kmath/expressions/DiffExpression.kt
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/expressions/DiffExpression.kt
@@ -1,6 +1,8 @@
-package scientifik.kmath.expressions
+package scientifik.kmath.commons.expressions
 
 import org.apache.commons.math3.analysis.differentiation.DerivativeStructure
+import scientifik.kmath.expressions.Expression
+import scientifik.kmath.expressions.ExpressionContext
 import scientifik.kmath.operations.ExtendedField
 import scientifik.kmath.operations.Field
 import kotlin.properties.ReadOnlyProperty
@@ -81,8 +83,12 @@ class DerivativeStructureField(
 /**
  * A constructs that creates a derivative structure with required order on-demand
  */
-class DiffExpression(val function: DerivativeStructureField.() -> DerivativeStructure) : Expression<Double> {
-    override fun invoke(arguments: Map<String, Double>): Double = DerivativeStructureField(0, arguments)
+class DiffExpression(val function: DerivativeStructureField.() -> DerivativeStructure) :
+    Expression<Double> {
+    override fun invoke(arguments: Map<String, Double>): Double = DerivativeStructureField(
+        0,
+        arguments
+    )
         .run(function).value
 
     /**
@@ -109,21 +115,27 @@ fun DiffExpression.derivative(name: String) = derivative(name to 1)
  * A context for [DiffExpression] (not to be confused with [DerivativeStructure])
  */
 object DiffExpressionContext : ExpressionContext<Double>, Field<DiffExpression> {
-    override fun variable(name: String, default: Double?) = DiffExpression { variable(name, default?.const()) }
+    override fun variable(name: String, default: Double?) =
+        DiffExpression { variable(name, default?.const()) }
 
-    override fun const(value: Double): DiffExpression = DiffExpression { value.const() }
+    override fun const(value: Double): DiffExpression =
+        DiffExpression { value.const() }
 
-    override fun add(a: DiffExpression, b: DiffExpression) = DiffExpression { a.function(this) + b.function(this) }
+    override fun add(a: DiffExpression, b: DiffExpression) =
+        DiffExpression { a.function(this) + b.function(this) }
 
     override val zero = DiffExpression { 0.0.const() }
 
-    override fun multiply(a: DiffExpression, k: Number) = DiffExpression { a.function(this) * k }
+    override fun multiply(a: DiffExpression, k: Number) =
+        DiffExpression { a.function(this) * k }
 
     override val one = DiffExpression { 1.0.const() }
 
-    override fun multiply(a: DiffExpression, b: DiffExpression) = DiffExpression { a.function(this) * b.function(this) }
+    override fun multiply(a: DiffExpression, b: DiffExpression) =
+        DiffExpression { a.function(this) * b.function(this) }
 
-    override fun divide(a: DiffExpression, b: DiffExpression) = DiffExpression { a.function(this) / b.function(this) }
+    override fun divide(a: DiffExpression, b: DiffExpression) =
+        DiffExpression { a.function(this) / b.function(this) }
 }
 
 
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/linear/CMMatrix.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/linear/CMMatrix.kt
similarity index 83%
rename from kmath-commons/src/main/kotlin/scientifik/kmath/linear/CMMatrix.kt
rename to kmath-commons/src/main/kotlin/scientifik/kmath/commons/linear/CMMatrix.kt
index 9103f0fb2..72e5fb95a 100644
--- a/kmath-commons/src/main/kotlin/scientifik/kmath/linear/CMMatrix.kt
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/linear/CMMatrix.kt
@@ -1,11 +1,13 @@
-package scientifik.kmath.linear
+package scientifik.kmath.commons.linear
 
 import org.apache.commons.math3.linear.*
 import org.apache.commons.math3.linear.RealMatrix
 import org.apache.commons.math3.linear.RealVector
+import scientifik.kmath.linear.*
 import scientifik.kmath.structures.Matrix
 
-class CMMatrix(val origin: RealMatrix, features: Set<MatrixFeature>? = null) : FeaturedMatrix<Double> {
+class CMMatrix(val origin: RealMatrix, features: Set<MatrixFeature>? = null) :
+    FeaturedMatrix<Double> {
     override val rowNum: Int get() = origin.rowDimension
     override val colNum: Int get() = origin.columnDimension
 
@@ -70,10 +72,14 @@ object CMMatrixContext : MatrixContext<Double> {
     override fun multiply(a: Matrix<Double>, k: Number) =
         CMMatrix(a.toCM().origin.scalarMultiply(k.toDouble()))
 
-    override fun Matrix<Double>.times(value: Double): Matrix<Double>  = produce(rowNum,colNum){i,j-> get(i,j)*value}
+    override fun Matrix<Double>.times(value: Double): Matrix<Double>  =
+        produce(rowNum, colNum) { i, j -> get(i, j) * value }
 }
 
-operator fun CMMatrix.plus(other: CMMatrix): CMMatrix = CMMatrix(this.origin.add(other.origin))
-operator fun CMMatrix.minus(other: CMMatrix): CMMatrix = CMMatrix(this.origin.subtract(other.origin))
+operator fun CMMatrix.plus(other: CMMatrix): CMMatrix =
+    CMMatrix(this.origin.add(other.origin))
+operator fun CMMatrix.minus(other: CMMatrix): CMMatrix =
+    CMMatrix(this.origin.subtract(other.origin))
 
-infix fun CMMatrix.dot(other: CMMatrix): CMMatrix = CMMatrix(this.origin.multiply(other.origin))
\ No newline at end of file
+infix fun CMMatrix.dot(other: CMMatrix): CMMatrix =
+    CMMatrix(this.origin.multiply(other.origin))
\ No newline at end of file
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/linear/CMSolver.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/linear/CMSolver.kt
similarity index 94%
rename from kmath-commons/src/main/kotlin/scientifik/kmath/linear/CMSolver.kt
rename to kmath-commons/src/main/kotlin/scientifik/kmath/commons/linear/CMSolver.kt
index a56e8c93e..77b688e31 100644
--- a/kmath-commons/src/main/kotlin/scientifik/kmath/linear/CMSolver.kt
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/linear/CMSolver.kt
@@ -1,6 +1,7 @@
-package scientifik.kmath.linear
+package scientifik.kmath.commons.linear
 
 import org.apache.commons.math3.linear.*
+import scientifik.kmath.linear.Point
 import scientifik.kmath.structures.Matrix
 
 enum class CMDecomposition {
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt
new file mode 100644
index 000000000..8267f8c73
--- /dev/null
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt
@@ -0,0 +1,18 @@
+package scientifik.kmath.commons.prob
+
+import org.apache.commons.math3.random.RandomGenerator
+
+inline class CMRandomGeneratorWrapper(val generator: RandomGenerator) : scientifik.kmath.prob.RandomGenerator {
+    override fun nextDouble(): Double = generator.nextDouble()
+
+    override fun nextInt(): Int = generator.nextInt()
+
+    override fun nextLong(): Long = generator.nextLong()
+
+    override fun nextBlock(size: Int): ByteArray = ByteArray(size).apply { generator.nextBytes(this) }
+}
+
+fun RandomGenerator.asKmathGenerator() = CMRandomGeneratorWrapper(this)
+
+fun scientifik.kmath.prob.RandomGenerator.asCMGenerator() =
+    (this as? CMRandomGeneratorWrapper)?.generator ?: TODO("Implement reverse CM wrapper")
\ No newline at end of file
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt
new file mode 100644
index 000000000..51de07975
--- /dev/null
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt
@@ -0,0 +1,84 @@
+package scientifik.kmath.commons.prob
+
+import org.apache.commons.math3.distribution.*
+import scientifik.kmath.chains.Chain
+import scientifik.kmath.chains.SimpleChain
+import scientifik.kmath.prob.Distribution
+import scientifik.kmath.prob.RandomChain
+import scientifik.kmath.prob.RandomGenerator
+import scientifik.kmath.prob.UnivariateDistribution
+import org.apache.commons.math3.random.RandomGenerator as CMRandom
+
+class CMRealDistributionWrapper(val builder: (CMRandom?) -> RealDistribution) : UnivariateDistribution<Double> {
+
+    private val defaultDistribution by lazy { builder(null) }
+
+    override fun probability(arg: Double): Double = defaultDistribution.probability(arg)
+
+    override fun cumulative(arg: Double): Double = defaultDistribution.cumulativeProbability(arg)
+
+    override fun sample(generator: RandomGenerator): RandomChain<Double> {
+        val distribution = builder(generator.asCMGenerator())
+        return RandomChain(generator) { distribution.sample() }
+    }
+}
+
+class CMIntDistributionWrapper(val builder: (CMRandom?) -> IntegerDistribution) : UnivariateDistribution<Int> {
+
+    private val defaultDistribution by lazy { builder(null) }
+
+    override fun probability(arg: Int): Double = defaultDistribution.probability(arg)
+
+    override fun cumulative(arg: Int): Double = defaultDistribution.cumulativeProbability(arg)
+
+    override fun sample(generator: RandomGenerator): RandomChain<Int> {
+        val distribution = builder(generator.asCMGenerator())
+        return RandomChain(generator) { distribution.sample() }
+    }
+}
+
+
+fun Distribution.Companion.normal(mean: Double, sigma: Double): UnivariateDistribution<Double> =
+    CMRealDistributionWrapper { generator -> NormalDistribution(generator, mean, sigma) }
+
+fun Distribution.Companion.poisson(mean: Double): UnivariateDistribution<Int> = CMIntDistributionWrapper { generator ->
+    PoissonDistribution(
+        generator,
+        mean,
+        PoissonDistribution.DEFAULT_EPSILON,
+        PoissonDistribution.DEFAULT_MAX_ITERATIONS
+    )
+}
+
+fun Distribution.Companion.binomial(trials: Int, p: Double): UnivariateDistribution<Int> =
+    CMIntDistributionWrapper { generator ->
+        BinomialDistribution(generator, trials, p)
+    }
+
+fun Distribution.Companion.student(degreesOfFreedom: Double): UnivariateDistribution<Double> =
+    CMRealDistributionWrapper { generator ->
+        TDistribution(generator, degreesOfFreedom, TDistribution.DEFAULT_INVERSE_ABSOLUTE_ACCURACY)
+    }
+
+fun Distribution.Companion.chi2(degreesOfFreedom: Double): UnivariateDistribution<Double> =
+    CMRealDistributionWrapper { generator ->
+        ChiSquaredDistribution(generator, degreesOfFreedom)
+    }
+
+fun Distribution.Companion.fisher(
+    numeratorDegreesOfFreedom: Double,
+    denominatorDegreesOfFreedom: Double
+): UnivariateDistribution<Double> =
+    CMRealDistributionWrapper { generator ->
+        FDistribution(generator, numeratorDegreesOfFreedom, denominatorDegreesOfFreedom)
+    }
+
+fun Distribution.Companion.exponential(mean: Double): UnivariateDistribution<Double> =
+    CMRealDistributionWrapper { generator ->
+        ExponentialDistribution(generator, mean)
+    }
+
+fun Distribution.Companion.uniform(a: Double, b: Double): UnivariateDistribution<Double> =
+    CMRealDistributionWrapper { generator ->
+        UniformRealDistribution(generator, a, b)
+    }
\ No newline at end of file
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/transform/Transformations.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/transform/Transformations.kt
similarity index 97%
rename from kmath-commons/src/main/kotlin/scientifik/kmath/transform/Transformations.kt
rename to kmath-commons/src/main/kotlin/scientifik/kmath/commons/transform/Transformations.kt
index ac6922262..ce51735fe 100644
--- a/kmath-commons/src/main/kotlin/scientifik/kmath/transform/Transformations.kt
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/transform/Transformations.kt
@@ -1,4 +1,4 @@
-package scientifik.kmath.transform
+package scientifik.kmath.commons.transform
 
 import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.Flow
diff --git a/kmath-commons/src/test/kotlin/scientifik/kmath/expressions/AutoDiffTest.kt b/kmath-commons/src/test/kotlin/scientifik/kmath/commons/expressions/AutoDiffTest.kt
similarity index 78%
rename from kmath-commons/src/test/kotlin/scientifik/kmath/expressions/AutoDiffTest.kt
rename to kmath-commons/src/test/kotlin/scientifik/kmath/commons/expressions/AutoDiffTest.kt
index 2695bb918..37e4e9ff9 100644
--- a/kmath-commons/src/test/kotlin/scientifik/kmath/expressions/AutoDiffTest.kt
+++ b/kmath-commons/src/test/kotlin/scientifik/kmath/commons/expressions/AutoDiffTest.kt
@@ -1,6 +1,9 @@
-package scientifik.kmath.expressions
+package scientifik.kmath.commons.expressions
 
 import org.junit.Test
+import scientifik.kmath.commons.expressions.DerivativeStructureField
+import scientifik.kmath.commons.expressions.DiffExpression
+import scientifik.kmath.commons.expressions.derivative
 import kotlin.test.assertEquals
 
 inline fun <R> diff(order: Int, vararg parameters: Pair<String, Double>, block: DerivativeStructureField.() -> R) =
diff --git a/kmath-prob/build.gradle.kts b/kmath-prob/build.gradle.kts
index 77a4aefc8..972b9bba0 100644
--- a/kmath-prob/build.gradle.kts
+++ b/kmath-prob/build.gradle.kts
@@ -13,7 +13,7 @@ kotlin.sourceSets {
     jvmMain {
         dependencies {
             // https://mvnrepository.com/artifact/org.apache.commons/commons-rng-simple
-            api("org.apache.commons:commons-rng-sampling:1.2")
+            //api("org.apache.commons:commons-rng-sampling:1.2")
             compileOnly("org.jetbrains.kotlinx:atomicfu:${Versions.atomicfuVersion}")
         }
     }
diff --git a/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt
index 946b173ff..a8614963b 100644
--- a/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt
+++ b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/Distribution.kt
@@ -16,8 +16,13 @@ interface Distribution<T : Any> {
      * Create a chain of samples from this distribution.
      * The chain is not guaranteed to be stateless.
      */
-    fun sample(generator: RandomGenerator): Chain<T>
+    fun sample(generator: RandomGenerator): RandomChain<T>
     //TODO add sample bunch generator
+
+    /**
+     * An empty companion. Distribution factories should be written as its extensions
+     */
+    companion object
 }
 
 interface UnivariateDistribution<T : Comparable<T>> : Distribution<T> {
@@ -25,4 +30,4 @@ interface UnivariateDistribution<T : Comparable<T>> : Distribution<T> {
      * Cumulative distribution for ordered parameter
      */
     fun cumulative(arg: T): Double
-}
\ No newline at end of file
+}
diff --git a/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomChain.kt b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomChain.kt
new file mode 100644
index 000000000..792b60603
--- /dev/null
+++ b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomChain.kt
@@ -0,0 +1,17 @@
+package scientifik.kmath.prob
+
+import kotlinx.atomicfu.atomic
+import scientifik.kmath.chains.Chain
+
+/**
+ * A possibly stateful chain producing random values.
+ * TODO make random chain properly fork generator
+ */
+class RandomChain<out R>(val generator: RandomGenerator, private val gen: suspend RandomGenerator.() -> R) : Chain<R> {
+    private val atomicValue = atomic<R?>(null)
+    override fun peek(): R? = atomicValue.value
+
+    override suspend fun next(): R = generator.gen().also { atomicValue.lazySet(it) }
+
+    override fun fork(): Chain<R> = RandomChain(generator, gen)
+}
\ No newline at end of file
diff --git a/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt b/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt
deleted file mode 100644
index c08008c28..000000000
--- a/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonDistributions.kt
+++ /dev/null
@@ -1,53 +0,0 @@
-package scientifik.kmath.prob
-
-import org.apache.commons.rng.sampling.distribution.*
-import scientifik.kmath.chains.Chain
-import scientifik.kmath.chains.SimpleChain
-import kotlin.math.PI
-import kotlin.math.exp
-import kotlin.math.sqrt
-
-class NormalDistribution(val mean: Double, val sigma: Double) : UnivariateDistribution<Double> {
-    enum class Sampler {
-        BoxMuller,
-        Marsaglia,
-        Ziggurat
-    }
-
-    override fun probability(arg: Double): Double {
-        val d = (arg - mean) / sigma
-        return 1.0 / sqrt(2.0 * PI * sigma) * exp(-d * d / 2)
-    }
-
-    override fun cumulative(arg: Double): Double {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    fun sample(generator: RandomGenerator, sampler: Sampler): Chain<Double> {
-        val normalized = when (sampler) {
-            Sampler.BoxMuller -> BoxMullerNormalizedGaussianSampler(generator.asProvider())
-            Sampler.Marsaglia -> MarsagliaNormalizedGaussianSampler(generator.asProvider())
-            Sampler.Ziggurat -> ZigguratNormalizedGaussianSampler(generator.asProvider())
-        }
-        val gauss = GaussianSampler(normalized, mean, sigma)
-        //TODO add generator to chain state to allow stateful forks
-        return SimpleChain { gauss.sample() }
-    }
-
-    override fun sample(generator: RandomGenerator): Chain<Double> = sample(generator, Sampler.BoxMuller)
-}
-
-class PoissonDistribution(val mean: Double): UnivariateDistribution<Int>{
-    override fun probability(arg: Int): Double {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    override fun cumulative(arg: Int): Double {
-        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
-    }
-
-    override fun sample(generator: RandomGenerator): Chain<Int> {
-        val sampler = PoissonSampler(generator.asProvider(), mean)
-        return SimpleChain{sampler.sample()}
-    }
-}
\ No newline at end of file
diff --git a/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt b/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt
deleted file mode 100644
index ad408460d..000000000
--- a/kmath-prob/src/jvmMain/kotlin/scientifik/kmath/prob/CommonsRandomProviderWrapper.kt
+++ /dev/null
@@ -1,18 +0,0 @@
-package scientifik.kmath.prob
-
-import org.apache.commons.rng.UniformRandomProvider
-
-inline class CommonsRandomProviderWrapper(val provider: UniformRandomProvider) : RandomGenerator {
-    override fun nextDouble(): Double = provider.nextDouble()
-
-    override fun nextInt(): Int = provider.nextInt()
-
-    override fun nextLong(): Long = provider.nextLong()
-
-    override fun nextBlock(size: Int): ByteArray = ByteArray(size).also { provider.nextBytes(it) }
-}
-
-fun UniformRandomProvider.asGenerator(): RandomGenerator = CommonsRandomProviderWrapper(this)
-
-fun RandomGenerator.asProvider(): UniformRandomProvider =
-    (this as? CommonsRandomProviderWrapper)?.provider ?: TODO("implement reverse wrapper")
\ No newline at end of file
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 5adf75fa5..efb1bf0d7 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -28,5 +28,5 @@ include(
     ":kmath-commons",
     ":kmath-koma",
     ":kmath-prob",
-    ":benchmarks"
+    ":examples"
 )

From f480aa1c5ca1e23dd811f10990ab832554ee1e56 Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Sat, 8 Jun 2019 16:25:51 +0300
Subject: [PATCH 3/5] Example fix

---
 build.gradle.kts                              |  2 +-
 examples/build.gradle                         | 39 -----------
 examples/build.gradle.kts                     | 67 +++++++++++++++++++
 .../kmath/structures/ArrayBenchmark.kt        |  6 +-
 .../kmath/structures/BufferBenchmark.kt       |  2 +-
 .../kmath/structures/NDFieldBenchmark.kt      |  5 +-
 .../kmath/commons/prob/DistributionDemo.kt    | 11 +++
 .../kmath/operations/ComplexDemo.kt           | 10 +++
 .../{ComplexNDBenchmark.kt => ComplexND.kt}   |  0
 .../kmath/structures/ComplexNDField.kt        |  5 +-
 .../scientifik/kmath/structures/NDAlgebra.kt  |  2 +
 settings.gradle.kts                           |  1 +
 12 files changed, 104 insertions(+), 46 deletions(-)
 delete mode 100644 examples/build.gradle
 create mode 100644 examples/build.gradle.kts
 rename examples/src/{jmh => benchmarks}/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt (95%)
 rename examples/src/{jmh => benchmarks}/kotlin/scientifik/kmath/structures/BufferBenchmark.kt (96%)
 rename examples/src/{jmh => benchmarks}/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt (89%)
 create mode 100644 examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt
 create mode 100644 examples/src/main/kotlin/scientifik/kmath/operations/ComplexDemo.kt
 rename examples/src/main/kotlin/scientifik/kmath/structures/{ComplexNDBenchmark.kt => ComplexND.kt} (100%)

diff --git a/build.gradle.kts b/build.gradle.kts
index 2fe3900ed..f3ea58b8e 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -5,7 +5,7 @@ allprojects {
         jcenter()
         maven("https://kotlin.bintray.com/kotlinx")
     }
-    
+
     group = "scientifik"
     version = kmathVersion
 }
diff --git a/examples/build.gradle b/examples/build.gradle
deleted file mode 100644
index 7c948e219..000000000
--- a/examples/build.gradle
+++ /dev/null
@@ -1,39 +0,0 @@
-plugins {
-    id "java"
-    id "me.champeau.gradle.jmh" version "0.4.8"
-    id 'org.jetbrains.kotlin.jvm'
-}
-
-repositories {
-    maven { url 'https://dl.bintray.com/kotlin/kotlin-eap' }
-    maven{ url "http://dl.bintray.com/kyonifer/maven"}
-    mavenCentral()
-}
-
-dependencies {
-    implementation project(":kmath-core")
-    implementation project(":kmath-coroutines")
-    implementation project(":kmath-commons")
-    implementation project(":kmath-koma")
-    implementation group: "com.kyonifer", name:"koma-core-ejml", version: "0.12"
-    implementation "org.jetbrains.kotlinx:kotlinx-io-jvm:0.1.5"
-    //compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
-    //jmh project(':kmath-core')
-}
-
-jmh {
-    warmupIterations = 1
-}
-
-jmhClasses.dependsOn(compileKotlin)
-
-compileKotlin {
-    kotlinOptions {
-        jvmTarget = "1.8"
-    }
-}
-compileTestKotlin {
-    kotlinOptions {
-        jvmTarget = "1.8"
-    }
-}
\ No newline at end of file
diff --git a/examples/build.gradle.kts b/examples/build.gradle.kts
new file mode 100644
index 000000000..7f6bec31f
--- /dev/null
+++ b/examples/build.gradle.kts
@@ -0,0 +1,67 @@
+import org.jetbrains.gradle.benchmarks.JvmBenchmarkTarget
+import org.jetbrains.kotlin.allopen.gradle.AllOpenExtension
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+    java
+    kotlin("jvm")
+    kotlin("plugin.allopen") version "1.3.31"
+    id("org.jetbrains.gradle.benchmarks.plugin") version "0.1.7-dev-24"
+}
+
+configure<AllOpenExtension> {
+    annotation("org.openjdk.jmh.annotations.State")
+}
+
+repositories {
+    maven("https://dl.bintray.com/kotlin/kotlin-eap")
+    maven("http://dl.bintray.com/kyonifer/maven")
+    maven("https://dl.bintray.com/orangy/maven")
+    mavenCentral()
+}
+
+sourceSets {
+    register("benchmarks")
+}
+
+dependencies {
+    implementation(project(":kmath-core"))
+    implementation(project(":kmath-coroutines"))
+    implementation(project(":kmath-commons"))
+    implementation(project(":kmath-koma"))
+    implementation("com.kyonifer:koma-core-ejml:0.12")
+    implementation("org.jetbrains.kotlinx:kotlinx-io-jvm:0.1.5")
+
+    implementation("org.jetbrains.gradle.benchmarks:runtime:0.1.7-dev-24")
+
+
+    "benchmarksCompile"(sourceSets.main.get().compileClasspath)
+}
+
+// Configure benchmark
+benchmark {
+    // Setup configurations
+    targets {
+        // This one matches sourceSet name above
+        register("benchmarks") {
+            this as JvmBenchmarkTarget
+            jmhVersion = "1.21"
+        }
+    }
+
+    configurations {
+        register("fast") {
+            warmups = 5 // number of warmup iterations
+            iterations = 3 // number of iterations
+            iterationTime = 500 // time in seconds per iteration
+            iterationTimeUnit = "ms" // time unity for iterationTime, default is seconds
+        }
+    }
+}
+
+
+tasks.withType<KotlinCompile> {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
\ No newline at end of file
diff --git a/examples/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
similarity index 95%
rename from examples/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
rename to examples/src/benchmarks/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
index 393d7b06a..d605e1b9c 100644
--- a/examples/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
+++ b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt
@@ -7,7 +7,7 @@ import java.nio.IntBuffer
 
 
 @State(Scope.Benchmark)
-open class ArrayBenchmark {
+class ArrayBenchmark {
 
     @Benchmark
     fun benchmarkArrayRead() {
@@ -32,10 +32,10 @@ open class ArrayBenchmark {
             res += nativeBuffer.get(size - i)
         }
     }
-    
+
     companion object {
         val size = 1000
-        
+
         val array = IntArray(size) { it }
         val arrayBuffer = IntBuffer.wrap(array)
         val nativeBuffer = IntBuffer.allocate(size).also {
diff --git a/examples/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
similarity index 96%
rename from examples/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
rename to examples/src/benchmarks/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
index a41ca83d3..9676b5e4a 100644
--- a/examples/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
+++ b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/BufferBenchmark.kt
@@ -7,7 +7,7 @@ import scientifik.kmath.operations.Complex
 import scientifik.kmath.operations.complex
 
 @State(Scope.Benchmark)
-open class BufferBenchmark {
+class BufferBenchmark {
 
     @Benchmark
     fun genericDoubleBufferReadWrite() {
diff --git a/examples/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
similarity index 89%
rename from examples/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
rename to examples/src/benchmarks/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
index 3e41323f1..9c2434bda 100644
--- a/examples/src/jmh/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
+++ b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
@@ -1,9 +1,12 @@
 package scientifik.kmath.structures
 
 import org.openjdk.jmh.annotations.Benchmark
+import org.openjdk.jmh.annotations.Scope
+import org.openjdk.jmh.annotations.State
 import scientifik.kmath.operations.RealField
 
-open class NDFieldBenchmark {
+@State(Scope.Benchmark)
+class NDFieldBenchmark {
 
     @Benchmark
     fun autoFieldAdd() {
diff --git a/examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt b/examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt
new file mode 100644
index 000000000..1db7643a0
--- /dev/null
+++ b/examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt
@@ -0,0 +1,11 @@
+package scientifik.kmath.commons.prob
+
+import kotlinx.coroutines.flow.take
+import scientifik.kmath.chains.flow
+import scientifik.kmath.prob.Distribution
+import scientifik.kmath.prob.RandomGenerator
+
+fun main() {
+    val normal = Distribution.normal()
+    normal.sample(RandomGenerator.default)
+}
\ No newline at end of file
diff --git a/examples/src/main/kotlin/scientifik/kmath/operations/ComplexDemo.kt b/examples/src/main/kotlin/scientifik/kmath/operations/ComplexDemo.kt
new file mode 100644
index 000000000..86b28303d
--- /dev/null
+++ b/examples/src/main/kotlin/scientifik/kmath/operations/ComplexDemo.kt
@@ -0,0 +1,10 @@
+package scientifik.kmath.operations
+
+import scientifik.kmath.structures.NDElement
+import scientifik.kmath.structures.complex
+
+fun main() {
+    val element = NDElement.complex(2, 2) { index: IntArray ->
+        Complex(index[0].toDouble() - index[1].toDouble(), index[0].toDouble() + index[1].toDouble())
+    }
+}
\ No newline at end of file
diff --git a/examples/src/main/kotlin/scientifik/kmath/structures/ComplexNDBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/structures/ComplexND.kt
similarity index 100%
rename from examples/src/main/kotlin/scientifik/kmath/structures/ComplexNDBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/structures/ComplexND.kt
diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/ComplexNDField.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/ComplexNDField.kt
index 6444f667d..e9d518bd5 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/ComplexNDField.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/ComplexNDField.kt
@@ -131,4 +131,7 @@ operator fun ComplexNDElement.plus(arg: Double) =
 operator fun ComplexNDElement.minus(arg: Double) =
     map { it - arg }
 
-fun NDField.Companion.complex(vararg shape: Int) = ComplexNDField(shape)
\ No newline at end of file
+fun NDField.Companion.complex(vararg shape: Int): ComplexNDField = ComplexNDField(shape)
+
+fun NDElement.Companion.complex(vararg shape: Int, initializer: ComplexField.(IntArray) -> Complex): ComplexNDElement =
+    NDField.complex(*shape).produce(initializer)
\ No newline at end of file
diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt
index c6f0f7a48..9857e4150 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt
@@ -57,6 +57,8 @@ interface NDAlgebra<T, C, N : NDStructure<T>> {
      * element-by-element invoke a function working on [T] on a [NDStructure]
      */
     operator fun Function1<T, T>.invoke(structure: N) = map(structure) { value -> this@invoke(value) }
+
+    companion object
 }
 
 /**
diff --git a/settings.gradle.kts b/settings.gradle.kts
index efb1bf0d7..004b432fd 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -3,6 +3,7 @@ pluginManagement {
         jcenter()
         gradlePluginPortal()
         maven("https://dl.bintray.com/kotlin/kotlin-eap")
+        maven("https://dl.bintray.com/orangy/maven")
     }
     resolutionStrategy {
         eachPlugin {

From cd1c155e7d896a637aedbdb3ae39b751b83c6d5a Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Sat, 8 Jun 2019 16:30:06 +0300
Subject: [PATCH 4/5] Examples fix

---
 doc/nd-structure.md                               | 15 +++++----------
 .../{NDFieldBenchmark.kt => NDField.kt}           |  0
 2 files changed, 5 insertions(+), 10 deletions(-)
 rename examples/src/main/kotlin/scientifik/kmath/structures/{NDFieldBenchmark.kt => NDField.kt} (100%)

diff --git a/doc/nd-structure.md b/doc/nd-structure.md
index b61609870..0b94bbdf8 100644
--- a/doc/nd-structure.md
+++ b/doc/nd-structure.md
@@ -9,15 +9,10 @@ structures. In `kmath` performance depends on which particular context was used
 
 Let us consider following contexts:
 ```kotlin
-    // specialized nd-field for Double. It works as generic Double field as well
-    val specializedField = NDField.real(intArrayOf(dim, dim))
-
     // automatically build context most suited for given type.
-    val autoField = NDField.auto(intArrayOf(dim, dim), RealField)
-
-    //A field implementing lazy computations. All elements are computed on-demand
-    val lazyField = NDField.lazy(intArrayOf(dim, dim), RealField)
-
+    val autoField = NDField.auto(RealField, dim, dim)
+    // specialized nd-field for Double. It works as generic Double field as well
+    val specializedField = NDField.real(dim, dim)
     //A generic boxing field. It should be used for objects, not primitives.
     val genericField = NDField.buffered(intArrayOf(dim, dim), RealField)
 ```
@@ -32,7 +27,7 @@ to it `n = 1000` times.
 The code to run this looks like:
 ```kotlin
     specializedField.run {
-        var res = one
+        var res: NDBuffer<Double> = one
         repeat(n) {
             res += 1.0
         }
@@ -93,7 +88,7 @@ In this case it completes in about `4x-5x` time due to boxing.
 The boxing field produced by
 ```kotlin
     genericField.run {
-        var res = one
+        var res: NDBuffer<Double> = one
         repeat(n) {
             res += 1.0
         }
diff --git a/examples/src/main/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt b/examples/src/main/kotlin/scientifik/kmath/structures/NDField.kt
similarity index 100%
rename from examples/src/main/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
rename to examples/src/main/kotlin/scientifik/kmath/structures/NDField.kt

From 1b647b60142f630342fe7ea61be3231d77a07b48 Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Sat, 8 Jun 2019 16:44:49 +0300
Subject: [PATCH 5/5] Random demo

---
 build.gradle.kts                              |  2 +-
 doc/nd-structure.md                           |  2 +-
 .../kmath/structures/NDFieldBenchmark.kt      |  2 +-
 .../kmath/commons/prob/DistributionDemo.kt    | 26 ++++++++++++++++---
 .../scientifik/kmath/structures/NDField.kt    |  2 +-
 .../commons/prob/CMRandomGeneratorWrapper.kt  | 20 ++++++++++----
 .../kmath/commons/prob/CommonsDistribution.kt |  4 +--
 .../scientifik/kmath/structures/NDAlgebra.kt  | 11 +++++---
 .../scientifik/kmath/prob/RandomGenerator.kt  |  2 ++
 9 files changed, 52 insertions(+), 19 deletions(-)

diff --git a/build.gradle.kts b/build.gradle.kts
index f3ea58b8e..d7b7ac78a 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,4 +1,4 @@
-val kmathVersion by extra("0.1.2")
+val kmathVersion by extra("0.1.3-dev-1")
 
 allprojects {
     repositories {
diff --git a/doc/nd-structure.md b/doc/nd-structure.md
index 0b94bbdf8..cf13c6a29 100644
--- a/doc/nd-structure.md
+++ b/doc/nd-structure.md
@@ -14,7 +14,7 @@ Let us consider following contexts:
     // specialized nd-field for Double. It works as generic Double field as well
     val specializedField = NDField.real(dim, dim)
     //A generic boxing field. It should be used for objects, not primitives.
-    val genericField = NDField.buffered(intArrayOf(dim, dim), RealField)
+    val genericField = NDField.buffered(RealField, dim, dim)
 ```
 Now let us perform several tests and see which implementation is best suited for each case:
 
diff --git a/examples/src/benchmarks/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
index 9c2434bda..46991b2de 100644
--- a/examples/src/benchmarks/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
+++ b/examples/src/benchmarks/kotlin/scientifik/kmath/structures/NDFieldBenchmark.kt
@@ -53,6 +53,6 @@ class NDFieldBenchmark {
 
         val bufferedField = NDField.auto(RealField, dim, dim)
         val specializedField = NDField.real(dim, dim)
-        val genericField = NDField.buffered(intArrayOf(dim, dim), RealField)
+        val genericField = NDField.buffered(RealField, dim, dim)
     }
 }
\ No newline at end of file
diff --git a/examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt b/examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt
index 1db7643a0..831a167bf 100644
--- a/examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt
+++ b/examples/src/main/kotlin/scientifik/kmath/commons/prob/DistributionDemo.kt
@@ -1,11 +1,31 @@
 package scientifik.kmath.commons.prob
 
-import kotlinx.coroutines.flow.take
-import scientifik.kmath.chains.flow
+import kotlinx.coroutines.runBlocking
+import scientifik.kmath.chains.Chain
+import scientifik.kmath.chains.StatefulChain
 import scientifik.kmath.prob.Distribution
 import scientifik.kmath.prob.RandomGenerator
 
+data class AveragingChainState(var num: Int = 0, var value: Double = 0.0)
+
+fun Chain<Double>.mean(): Chain<Double> = StatefulChain(AveragingChainState(), 0.0) {
+    val next = this@mean.next()
+    num++
+    value += next
+    return@StatefulChain value / num
+}
+
+
 fun main() {
     val normal = Distribution.normal()
-    normal.sample(RandomGenerator.default)
+    val chain = normal.sample(RandomGenerator.default).mean()
+
+    runBlocking {
+        repeat(10001) { counter ->
+            val mean = chain.next()
+            if(counter % 1000 ==0){
+                println("[$counter] Average value is $mean")
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/examples/src/main/kotlin/scientifik/kmath/structures/NDField.kt b/examples/src/main/kotlin/scientifik/kmath/structures/NDField.kt
index 53a23c2bc..10fad3ecb 100644
--- a/examples/src/main/kotlin/scientifik/kmath/structures/NDField.kt
+++ b/examples/src/main/kotlin/scientifik/kmath/structures/NDField.kt
@@ -13,7 +13,7 @@ fun main(args: Array<String>) {
     // specialized nd-field for Double. It works as generic Double field as well
     val specializedField = NDField.real(dim, dim)
     //A generic boxing field. It should be used for objects, not primitives.
-    val genericField = NDField.buffered(intArrayOf(dim, dim), RealField)
+    val genericField = NDField.buffered(RealField, dim, dim)
 
 
     val autoTime = measureTimeMillis {
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt
index 8267f8c73..a32626e0d 100644
--- a/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CMRandomGeneratorWrapper.kt
@@ -1,8 +1,10 @@
 package scientifik.kmath.commons.prob
 
-import org.apache.commons.math3.random.RandomGenerator
+import org.apache.commons.math3.random.JDKRandomGenerator
+import scientifik.kmath.prob.RandomGenerator
+import org.apache.commons.math3.random.RandomGenerator as CMRandom
 
-inline class CMRandomGeneratorWrapper(val generator: RandomGenerator) : scientifik.kmath.prob.RandomGenerator {
+inline class CMRandomGeneratorWrapper(val generator: CMRandom) : RandomGenerator {
     override fun nextDouble(): Double = generator.nextDouble()
 
     override fun nextInt(): Int = generator.nextInt()
@@ -12,7 +14,15 @@ inline class CMRandomGeneratorWrapper(val generator: RandomGenerator) : scientif
     override fun nextBlock(size: Int): ByteArray = ByteArray(size).apply { generator.nextBytes(this) }
 }
 
-fun RandomGenerator.asKmathGenerator() = CMRandomGeneratorWrapper(this)
+fun CMRandom.asKmathGenerator(): RandomGenerator = CMRandomGeneratorWrapper(this)
 
-fun scientifik.kmath.prob.RandomGenerator.asCMGenerator() =
-    (this as? CMRandomGeneratorWrapper)?.generator ?: TODO("Implement reverse CM wrapper")
\ No newline at end of file
+fun RandomGenerator.asCMGenerator(): CMRandom =
+    (this as? CMRandomGeneratorWrapper)?.generator ?: TODO("Implement reverse CM wrapper")
+
+val RandomGenerator.Companion.default: RandomGenerator by lazy { JDKRandomGenerator().asKmathGenerator() }
+
+fun RandomGenerator.Companion.jdk(seed: Int? = null): RandomGenerator = if (seed == null) {
+    JDKRandomGenerator()
+} else {
+    JDKRandomGenerator(seed)
+}.asKmathGenerator()
\ No newline at end of file
diff --git a/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt
index 51de07975..94f8560a4 100644
--- a/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt
+++ b/kmath-commons/src/main/kotlin/scientifik/kmath/commons/prob/CommonsDistribution.kt
@@ -1,8 +1,6 @@
 package scientifik.kmath.commons.prob
 
 import org.apache.commons.math3.distribution.*
-import scientifik.kmath.chains.Chain
-import scientifik.kmath.chains.SimpleChain
 import scientifik.kmath.prob.Distribution
 import scientifik.kmath.prob.RandomChain
 import scientifik.kmath.prob.RandomGenerator
@@ -38,7 +36,7 @@ class CMIntDistributionWrapper(val builder: (CMRandom?) -> IntegerDistribution)
 }
 
 
-fun Distribution.Companion.normal(mean: Double, sigma: Double): UnivariateDistribution<Double> =
+fun Distribution.Companion.normal(mean: Double = 0.0, sigma: Double = 1.0): UnivariateDistribution<Double> =
     CMRealDistributionWrapper { generator -> NormalDistribution(generator, mean, sigma) }
 
 fun Distribution.Companion.poisson(mean: Double): UnivariateDistribution<Int> = CMIntDistributionWrapper { generator ->
diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt
index 9857e4150..352c05467 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt
@@ -1,9 +1,9 @@
 package scientifik.kmath.structures
 
+import scientifik.kmath.operations.Complex
 import scientifik.kmath.operations.Field
 import scientifik.kmath.operations.Ring
 import scientifik.kmath.operations.Space
-import kotlin.jvm.JvmName
 
 
 /**
@@ -77,6 +77,7 @@ interface NDSpace<T, S : Space<T>, N : NDStructure<T>> : Space<N>, NDAlgebra<T,
 
     //TODO move to extensions after KEEP-176
     operator fun N.plus(arg: T) = map(this) { value -> add(arg, value) }
+
     operator fun N.minus(arg: T) = map(this) { value -> add(arg, -value) }
 
     operator fun T.plus(arg: N) = map(arg) { value -> add(this@plus, value) }
@@ -95,6 +96,7 @@ interface NDRing<T, R : Ring<T>, N : NDStructure<T>> : Ring<N>, NDSpace<T, R, N>
 
     //TODO move to extensions after KEEP-176
     operator fun N.times(arg: T) = map(this) { value -> multiply(arg, value) }
+
     operator fun T.times(arg: N) = map(arg) { value -> multiply(this@times, value) }
 }
 
@@ -115,6 +117,7 @@ interface NDField<T, F : Field<T>, N : NDStructure<T>> : Field<N>, NDRing<T, F,
 
     //TODO move to extensions after KEEP-176
     operator fun N.div(arg: T) = map(this) { value -> divide(arg, value) }
+
     operator fun T.div(arg: N) = map(arg) { divide(it, this@div) }
 
     companion object {
@@ -130,11 +133,10 @@ interface NDField<T, F : Field<T>, N : NDStructure<T>> : Field<N>, NDRing<T, F,
          * Create a nd-field with boxing generic buffer
          */
         fun <T : Any, F : Field<T>> buffered(
-            shape: IntArray,
             field: F,
+            vararg shape: Int,
             bufferFactory: BufferFactory<T> = Buffer.Companion::boxing
-        ) =
-            BoxingNDField(shape, field, bufferFactory)
+        ) = BoxingNDField(shape, field, bufferFactory)
 
         /**
          * Create a most suitable implementation for nd-field using reified class.
@@ -143,6 +145,7 @@ interface NDField<T, F : Field<T>, N : NDStructure<T>> : Field<N>, NDRing<T, F,
         inline fun <reified T : Any, F : Field<T>> auto(field: F, vararg shape: Int): BufferedNDField<T, F> =
             when {
                 T::class == Double::class -> real(*shape) as BufferedNDField<T, F>
+                T::class == Complex::class -> complex(*shape) as BufferedNDField<T, F>
                 else -> BoxingNDField(shape, field, Buffer.Companion::auto)
             }
     }
diff --git a/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt
index 89cbc615c..039ee3d2b 100644
--- a/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt
+++ b/kmath-prob/src/commonMain/kotlin/scientifik/kmath/prob/RandomGenerator.kt
@@ -8,4 +8,6 @@ interface RandomGenerator {
     fun nextInt(): Int
     fun nextLong(): Long
     fun nextBlock(size: Int): ByteArray
+
+    companion object
 }
\ No newline at end of file