build.gradle.kts

@@ -22,8 +22,8 @@ plugins {
 }
 
 allprojects {
-    apply(plugin = "maven-publish")
-    if(project.name.startsWith("kmath")) {
+    if (project.name.startsWith("kmath")) {
+        apply(plugin = "maven-publish")
         apply(plugin = "com.jfrog.artifactory")
     }
 

doc/buffers.md

@@ -0,0 +1 @@
+**TODO**

doc/expressions.md

@@ -0,0 +1,26 @@
+# Expressions
+
+**Experimental: this API is in early stage and could change any time**
+
+Expressions is an experimental feature which allows to construct lazily or immediately calculated parametric mathematical 
+expressions.
+
+The potential use-cases for it (so far) are following:
+
+* Lazy evaluation (in general simple lambda is better, but there are some border cases)
+
+* Automatic differentiation in single-dimension and in multiple dimensions
+
+* Generation of mathematical syntax trees with subsequent code generation for other languages
+
+* Maybe symbolic computations (needs additional research)
+
+The workhorse of this API is `Expression` interface which exposes single `operator fun invoke(arguments: Map<String, T>): T`
+method. `ExpressionContext` is used to generate expressions and introduce variables.
+
+Currently there are two implementations:
+
+* Generic `ExpressionField` in `kmath-core` which allows construction of custom lazy expressions
+
+* Auto-differentiation expression in `kmath-commons` module allows to use full power of `DerivativeStructure` 
+from commons-math. **TODO: add example**

doc/histograms.md

@@ -0,0 +1 @@
+**TODO**

doc/operations.md

@@ -14,7 +14,7 @@ val c3 = c1 + c2
 `ComplexField` also features special operations to mix complex and real numbers, for example:
 
 ```kotlin
-val c1 = Complex(1.0,2.0)
+val c1 = Complex(1.0, 2.0)
 val c2 = ComplexField.run{ c1 - 1.0} // Returns: [re:0.0, im: 2.0]
 val c3 = ComplexField.run{ c1 - i*2.0}
 ```
@@ -27,8 +27,8 @@ that. Watch [KT-10468](https://youtrack.jetbrains.com/issue/KT-10468) and [KEEP-
 Contexts allow one to build more complex structures. For example, it is possible to create a `Matrix` from complex elements like so:
 
 ```kotlin
-val element = NDElements.create(field = ComplexField, shape = intArrayOf(2,2)){index: IntArray ->
-    Complex(index[0] - index[1], index[0] + index[1])
+val element = NDElement.complex(shape = intArrayOf(2,2)){ index: IntArray ->
+    Complex(index[0].toDouble() - index[1].toDouble(), index[0].toDouble() + index[1].toDouble())
 }
 ```
 

examples/build.gradle.kts

@@ -1,15 +0,0 @@
-plugins {
-    kotlin("jvm")
-}
-
-description = "Examples for different kmath features"
-
-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")
-    testImplementation("org.jetbrains.kotlin:kotlin-test")
-    testImplementation("org.jetbrains.kotlin:kotlin-test-junit")
-}

examples/expressions.main.kts

@@ -0,0 +1 @@
+@file:DependsOn("scientifik:kmath-core-jvm:0.0.3-dev")

kmath-commons/src/main/kotlin/scientifik/kmath/expressions/DiffExpression.kt

@@ -2,6 +2,7 @@ package scientifik.kmath.expressions
 
 import org.apache.commons.math3.analysis.differentiation.DerivativeStructure
 import scientifik.kmath.operations.ExtendedField
+import scientifik.kmath.operations.Field
 import kotlin.properties.ReadOnlyProperty
 import kotlin.reflect.KProperty
 
@@ -25,8 +26,8 @@ class DerivativeStructureField(val order: Int, val parameters: Map<String, Doubl
         }
     }
 
-    fun variable(name: String): DerivativeStructure =
-        variables[name] ?: error("A variable with name ${name} does not exist")
+    fun variable(name: String, default: DerivativeStructure? = null): DerivativeStructure =
+        variables[name] ?: default ?: error("A variable with name $name does not exist")
 
 
     fun Number.const() = DerivativeStructure(order, parameters.size, toDouble())
@@ -102,5 +103,26 @@ class DiffExpression(val function: DerivativeStructureField.() -> DerivativeStru
 fun DiffExpression.derivative(vararg orders: Pair<String, Int>) = derivative(mapOf(*orders))
 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 const(value: Double): DiffExpression = DiffExpression { value.const() }
+
+    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 val one = DiffExpression { 1.0.const() }
+
+    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) }
+}
+
 
 

kmath-core/src/commonMain/kotlin/scientifik/kmath/expressions/Expression.kt

@@ -4,16 +4,27 @@ import scientifik.kmath.operations.Field
 import scientifik.kmath.operations.Ring
 import scientifik.kmath.operations.Space
 
-
+/**
+ * An elementary function that could be invoked on a map of arguments
+ */
 interface Expression<T> {
     operator fun invoke(arguments: Map<String, T>): T
 }
 
 operator fun <T> Expression<T>.invoke(vararg pairs: Pair<String, T>): T = invoke(mapOf(*pairs))
 
+/**
+ * A context for expression construction
+ */
 interface ExpressionContext<T> {
+    /**
+     * Introduce a variable into expression context
+     */
     fun variable(name: String, default: T? = null): Expression<T>
 
+    /**
+     * A constant expression which does not depend on arguments
+     */
     fun const(value: T): Expression<T>
 }
 

kmath-coroutines/src/commonTest/kotlin/scientifik/kmath/structures/LazyNDFieldTest.kt

@@ -1,16 +0,0 @@
-package scientifik.kmath.structures
-
-
-class LazyNDFieldTest {
-//    @Test
-//    fun testLazyStructure() {
-//        var counter = 0
-//        val regularStructure = NDField.auto(intArrayOf(2, 2, 2), IntRing).produce { it[0] + it[1] - it[2] }
-//        val result = (regularStructure.lazy(IntRing) + 2).map {
-//            counter++
-//            it * it
-//        }
-//        assertEquals(4, result[0, 0, 0])
-//        assertEquals(1, counter)
-//    }
-}

settings.gradle.kts

@@ -25,6 +25,5 @@ include(
     ":kmath-commons",
     ":kmath-koma",
     ":kmath-sequential",
-    ":benchmarks",
-    ":examples"
+    ":benchmarks"
 )