benchmarks/src/main/kotlin/scientifik/kmath/structures/StructureWriteBenchmark.kt

@@ -8,7 +8,7 @@ fun main(args: Array<String>) {
 
     val n = 6000
 
-    val structure = ndStructure(intArrayOf(n, n), DoubleBufferFactory) { 1.0 }
+    val structure = NDStructure.build(intArrayOf(n, n), DoubleBufferFactory) { 1.0 }
 
     structure.mapToBuffer { it + 1 } // warm-up
 

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.ExtendedFieldOperations
 import scientifik.kmath.operations.Field
 import kotlin.properties.ReadOnlyProperty
 import kotlin.reflect.KProperty

kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Complex.kt

@@ -5,7 +5,7 @@ import kotlin.math.*
 /**
  * A field for complex numbers
  */
-object ComplexField : ExtendedField<Complex> {
+object ComplexField : ExtendedFieldOperations<Complex>, Field<Complex> {
     override val zero: Complex = Complex(0.0, 0.0)
 
     override val one: Complex = Complex(1.0, 0.0)

kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/NumberAlgebra.kt

@@ -5,12 +5,13 @@ import kotlin.math.pow
 /**
  * Advanced Number-like field that implements basic operations
  */
-interface ExtendedField<T : Any> :
+interface ExtendedFieldOperations<T> :
-    Field<T>,
+    FieldOperations<T>,
     TrigonometricOperations<T>,
     PowerOperations<T>,
     ExponentialOperations<T>
 
+interface ExtendedField<T> : ExtendedFieldOperations<T>, Field<T>
 
 /**
  * Real field element wrapping double.
@@ -31,7 +32,7 @@ inline class Real(val value: Double) : FieldElement<Double, Real, RealField> {
  * A field for double without boxing. Does not produce appropriate field element
  */
 @Suppress("EXTENSION_SHADOWED_BY_MEMBER")
-object RealField : ExtendedField<Double>, Norm<Double, Double> {
+object RealField : Field<Double>, ExtendedFieldOperations<Double>, Norm<Double, Double> {
     override val zero: Double = 0.0
     override fun add(a: Double, b: Double): Double = a + b
     override fun multiply(a: Double, b: Double): Double = a * b

kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/OptionalOperations.kt

@@ -10,7 +10,7 @@ package scientifik.kmath.operations
  * It also allows to override behavior for optional operations
  *
  */
-interface TrigonometricOperations<T> : Field<T> {
+interface TrigonometricOperations<T> : FieldOperations<T> {
     fun sin(arg: T): T
     fun cos(arg: T): T
 

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/Buffers.kt

@@ -109,6 +109,9 @@ inline class ListBuffer<T>(val list: List<T>) : Buffer<T> {
 
 fun <T> List<T>.asBuffer() = ListBuffer(this)
 
+@Suppress("FunctionName")
+inline fun <T> ListBuffer(size: Int, init: (Int) -> T) = List(size, init).asBuffer()
+
 inline class MutableListBuffer<T>(val list: MutableList<T>) : MutableBuffer<T> {
 
     override val size: Int
@@ -154,9 +157,12 @@ inline class DoubleBuffer(val array: DoubleArray) : MutableBuffer<Double> {
     override fun iterator(): Iterator<Double> = array.iterator()
 
     override fun copy(): MutableBuffer<Double> = DoubleBuffer(array.copyOf())
-
 }
 
+@Suppress("FunctionName")
+inline fun DoubleBuffer(size: Int, init: (Int) -> Double) = DoubleBuffer(DoubleArray(size) { init(it) })
+
+
 /**
  * Transform buffer of doubles into array for high performance operations
  */

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/ExtendedNDField.kt

@@ -1,16 +1,14 @@
 package scientifik.kmath.structures
 
-import scientifik.kmath.operations.ExponentialOperations
+import scientifik.kmath.operations.*
-import scientifik.kmath.operations.ExtendedField
-import scientifik.kmath.operations.PowerOperations
-import scientifik.kmath.operations.TrigonometricOperations
 
 
-interface ExtendedNDField<T : Any, F : ExtendedField<T>, N : NDStructure<T>> :
+interface ExtendedNDField<T : Any, F, N : NDStructure<T>> :
     NDField<T, F, N>,
     TrigonometricOperations<N>,
     PowerOperations<N>,
     ExponentialOperations<N>
+        where F : ExtendedFieldOperations<T>, F : Field<T>
 
 
 ///**

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDStructure.kt

@@ -22,6 +22,33 @@ interface NDStructure<T> {
                 else -> st1.elements().all { (index, value) -> value == st2[index] }
             }
         }
+
+        /**
+         * Create a NDStructure with explicit buffer factory
+         *
+         * Strides should be reused if possible
+         */
+        fun <T> build(
+            strides: Strides,
+            bufferFactory: BufferFactory<T> = Buffer.Companion::boxing,
+            initializer: (IntArray) -> T
+        ) =
+            BufferNDStructure(strides, bufferFactory(strides.linearSize) { i -> initializer(strides.index(i)) })
+
+        /**
+         * Inline create NDStructure with non-boxing buffer implementation if it is possible
+         */
+        inline fun <reified T : Any> auto(strides: Strides, crossinline initializer: (IntArray) -> T) =
+            BufferNDStructure(strides, Buffer.auto(strides.linearSize) { i -> initializer(strides.index(i)) })
+
+        fun <T> build(
+            shape: IntArray,
+            bufferFactory: BufferFactory<T> = Buffer.Companion::boxing,
+            initializer: (IntArray) -> T
+        ) = build(DefaultStrides(shape), bufferFactory, initializer)
+
+        inline fun <reified T : Any> auto(shape: IntArray, crossinline initializer: (IntArray) -> T) =
+            auto(DefaultStrides(shape), initializer)
     }
 }
 
@@ -200,34 +227,6 @@ inline fun <T, reified R : Any> NDStructure<T>.mapToBuffer(
     }
 }
 
-/**
- * Create a NDStructure with explicit buffer factory
- *
- * Strides should be reused if possible
- */
-fun <T> ndStructure(
-    strides: Strides,
-    bufferFactory: BufferFactory<T> = Buffer.Companion::boxing,
-    initializer: (IntArray) -> T
-) =
-    BufferNDStructure(strides, bufferFactory(strides.linearSize) { i -> initializer(strides.index(i)) })
-
-/**
- * Inline create NDStructure with non-boxing buffer implementation if it is possible
- */
-inline fun <reified T : Any> inlineNDStructure(strides: Strides, crossinline initializer: (IntArray) -> T) =
-    BufferNDStructure(strides, Buffer.auto(strides.linearSize) { i -> initializer(strides.index(i)) })
-
-fun <T> ndStructure(
-    shape: IntArray,
-    bufferFactory: BufferFactory<T> = Buffer.Companion::boxing,
-    initializer: (IntArray) -> T
-) =
-    ndStructure(DefaultStrides(shape), bufferFactory, initializer)
-
-inline fun <reified T : Any> inlineNdStructure(shape: IntArray, crossinline initializer: (IntArray) -> T) =
-    inlineNDStructure(DefaultStrides(shape), initializer)
-
 /**
  * Mutable ND buffer based on linear [autoBuffer]
  */
@@ -245,33 +244,10 @@ class MutableBufferNDStructure<T>(
     override fun set(index: IntArray, value: T) = buffer.set(strides.offset(index), value)
 }
 
-/**
- * The same as [inlineNDStructure], but mutable
- */
-fun <T : Any> mutableNdStructure(
-    strides: Strides,
-    bufferFactory: MutableBufferFactory<T> = MutableBuffer.Companion::boxing,
-    initializer: (IntArray) -> T
-) =
-    MutableBufferNDStructure(strides, bufferFactory(strides.linearSize) { i -> initializer(strides.index(i)) })
-
-inline fun <reified T : Any> inlineMutableNdStructure(strides: Strides, crossinline initializer: (IntArray) -> T) =
-    MutableBufferNDStructure(strides, MutableBuffer.auto(strides.linearSize) { i -> initializer(strides.index(i)) })
-
-fun <T : Any> mutableNdStructure(
-    shape: IntArray,
-    bufferFactory: MutableBufferFactory<T> = MutableBuffer.Companion::boxing,
-    initializer: (IntArray) -> T
-) =
-    mutableNdStructure(DefaultStrides(shape), bufferFactory, initializer)
-
-inline fun <reified T : Any> inlineMutableNdStructure(shape: IntArray, crossinline initializer: (IntArray) -> T) =
-    inlineMutableNdStructure(DefaultStrides(shape), initializer)
-
 inline fun <reified T : Any> NDStructure<T>.combine(
     struct: NDStructure<T>,
     crossinline block: (T, T) -> T
 ): NDStructure<T> {
     if (!this.shape.contentEquals(struct.shape)) error("Shape mismatch in structure combination")
-    return inlineNdStructure(shape) { block(this[it], struct[it]) }
+    return NDStructure.auto(shape) { block(this[it], struct[it]) }
 }

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/RealBufferField.kt

@@ -1,110 +1,153 @@
 package scientifik.kmath.structures
 
-import scientifik.kmath.operations.ExtendedField
+import scientifik.kmath.operations.ExtendedFieldOperations
+import scientifik.kmath.operations.Field
 import kotlin.math.*
 
+
 /**
  * A simple field over linear buffers of [Double]
  */
-class RealBufferField(val size: Int) : ExtendedField<Buffer<Double>> {
+object RealBufferFieldOperations : ExtendedFieldOperations<Buffer<Double>> {
-    override val zero: Buffer<Double> = Buffer.DoubleBufferFactory(size) { 0.0 }
-
-    override val one: Buffer<Double> = Buffer.DoubleBufferFactory(size) { 1.0 }
-
     override fun add(a: Buffer<Double>, b: Buffer<Double>): DoubleBuffer {
-        require(a.size == size) { "The size of buffer is ${a.size} but context requires $size " }
+        require(b.size == a.size) { "The size of the first buffer ${a.size} should be the same as for second one: ${b.size} " }
-        require(b.size == size) { "The size of buffer is ${b.size} but context requires $size " }
         return if (a is DoubleBuffer && b is DoubleBuffer) {
             val aArray = a.array
             val bArray = b.array
-            DoubleBuffer(DoubleArray(size) { aArray[it] + bArray[it] })
+            DoubleBuffer(DoubleArray(a.size) { aArray[it] + bArray[it] })
         } else {
-            DoubleBuffer(DoubleArray(size) { a[it] + b[it] })
+            DoubleBuffer(DoubleArray(a.size) { a[it] + b[it] })
         }
     }
 
     override fun multiply(a: Buffer<Double>, k: Number): DoubleBuffer {
-        require(a.size == size) { "The size of buffer is ${a.size} but context requires $size " }
         val kValue = k.toDouble()
         return if (a is DoubleBuffer) {
             val aArray = a.array
-            DoubleBuffer(DoubleArray(size) { aArray[it] * kValue })
+            DoubleBuffer(DoubleArray(a.size) { aArray[it] * kValue })
         } else {
-            DoubleBuffer(DoubleArray(size) { a[it] * kValue })
+            DoubleBuffer(DoubleArray(a.size) { a[it] * kValue })
         }
     }
 
     override fun multiply(a: Buffer<Double>, b: Buffer<Double>): DoubleBuffer {
-        require(a.size == size) { "The size of buffer is ${a.size} but context requires $size " }
+        require(b.size == a.size) { "The size of the first buffer ${a.size} should be the same as for second one: ${b.size} " }
-        require(b.size == size) { "The size of buffer is ${b.size} but context requires $size " }
         return if (a is DoubleBuffer && b is DoubleBuffer) {
             val aArray = a.array
             val bArray = b.array
-            DoubleBuffer(DoubleArray(size) { aArray[it] * bArray[it] })
+            DoubleBuffer(DoubleArray(a.size) { aArray[it] * bArray[it] })
         } else {
-            DoubleBuffer(DoubleArray(size) { a[it] * b[it] })
+            DoubleBuffer(DoubleArray(a.size) { a[it] * b[it] })
         }
     }
 
     override fun divide(a: Buffer<Double>, b: Buffer<Double>): DoubleBuffer {
-        require(a.size == size) { "The size of buffer is ${a.size} but context requires $size " }
+        require(b.size == a.size) { "The size of the first buffer ${a.size} should be the same as for second one: ${b.size} " }
-        require(b.size == size) { "The size of buffer is ${b.size} but context requires $size " }
         return if (a is DoubleBuffer && b is DoubleBuffer) {
             val aArray = a.array
             val bArray = b.array
-            DoubleBuffer(DoubleArray(size) { aArray[it] / bArray[it] })
+            DoubleBuffer(DoubleArray(a.size) { aArray[it] / bArray[it] })
         } else {
-            DoubleBuffer(DoubleArray(size) { a[it] / b[it] })
+            DoubleBuffer(DoubleArray(a.size) { a[it] / b[it] })
         }
     }
 
-    override fun sin(arg: Buffer<Double>): Buffer<Double> {
+    override fun sin(arg: Buffer<Double>): DoubleBuffer {
-        require(arg.size == size) { "The size of buffer is ${arg.size} but context requires $size " }
         return if (arg is DoubleBuffer) {
             val array = arg.array
-            DoubleBuffer(DoubleArray(size) { sin(array[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { sin(array[it]) })
         } else {
-            DoubleBuffer(DoubleArray(size) { sin(arg[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { sin(arg[it]) })
         }
     }
 
-    override fun cos(arg: Buffer<Double>): Buffer<Double> {
+    override fun cos(arg: Buffer<Double>): DoubleBuffer {
-        require(arg.size == size) { "The size of buffer is ${arg.size} but context requires $size " }
         return if (arg is DoubleBuffer) {
             val array = arg.array
-            DoubleBuffer(DoubleArray(size) { cos(array[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { cos(array[it]) })
         } else {
-            DoubleBuffer(DoubleArray(size) { cos(arg[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { cos(arg[it]) })
         }
     }
 
-    override fun power(arg: Buffer<Double>, pow: Number): Buffer<Double> {
+    override fun power(arg: Buffer<Double>, pow: Number): DoubleBuffer {
-        require(arg.size == size) { "The size of buffer is ${arg.size} but context requires $size " }
         return if (arg is DoubleBuffer) {
             val array = arg.array
-            DoubleBuffer(DoubleArray(size) { array[it].pow(pow.toDouble()) })
+            DoubleBuffer(DoubleArray(arg.size) { array[it].pow(pow.toDouble()) })
         } else {
-            DoubleBuffer(DoubleArray(size) { arg[it].pow(pow.toDouble()) })
+            DoubleBuffer(DoubleArray(arg.size) { arg[it].pow(pow.toDouble()) })
         }
     }
 
-    override fun exp(arg: Buffer<Double>): Buffer<Double> {
+    override fun exp(arg: Buffer<Double>): DoubleBuffer {
-        require(arg.size == size) { "The size of buffer is ${arg.size} but context requires $size " }
         return if (arg is DoubleBuffer) {
             val array = arg.array
-            DoubleBuffer(DoubleArray(size) { exp(array[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { exp(array[it]) })
         } else {
-            DoubleBuffer(DoubleArray(size) { exp(arg[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { exp(arg[it]) })
         }
     }
 
-    override fun ln(arg: Buffer<Double>): Buffer<Double> {
+    override fun ln(arg: Buffer<Double>): DoubleBuffer {
-        require(arg.size == size) { "The size of buffer is ${arg.size} but context requires $size " }
         return if (arg is DoubleBuffer) {
             val array = arg.array
-            DoubleBuffer(DoubleArray(size) { ln(array[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { ln(array[it]) })
         } else {
-            DoubleBuffer(DoubleArray(size) { ln(arg[it]) })
+            DoubleBuffer(DoubleArray(arg.size) { ln(arg[it]) })
         }
     }
+}
+
+class RealBufferField(val size: Int) : Field<Buffer<Double>>, ExtendedFieldOperations<Buffer<Double>> {
+
+    override val zero: Buffer<Double> by lazy { DoubleBuffer(size) { 0.0 } }
+
+    override val one: Buffer<Double> by lazy { DoubleBuffer(size) { 1.0 } }
+
+    override fun add(a: Buffer<Double>, b: Buffer<Double>): DoubleBuffer {
+        require(a.size == size) { "The buffer size ${a.size} does not match context size $size" }
+        return RealBufferFieldOperations.add(a, b)
+    }
+
+    override fun multiply(a: Buffer<Double>, k: Number): DoubleBuffer {
+        require(a.size == size) { "The buffer size ${a.size} does not match context size $size" }
+        return RealBufferFieldOperations.multiply(a, k)
+    }
+
+    override fun multiply(a: Buffer<Double>, b: Buffer<Double>): DoubleBuffer {
+        require(a.size == size) { "The buffer size ${a.size} does not match context size $size" }
+        return RealBufferFieldOperations.multiply(a, b)
+    }
+
+
+    override fun divide(a: Buffer<Double>, b: Buffer<Double>): DoubleBuffer {
+        require(a.size == size) { "The buffer size ${a.size} does not match context size $size" }
+        return RealBufferFieldOperations.divide(a, b)
+    }
+
+    override fun sin(arg: Buffer<Double>): DoubleBuffer {
+        require(arg.size == size) { "The buffer size ${arg.size} does not match context size $size" }
+        return RealBufferFieldOperations.sin(arg)
+    }
+
+    override fun cos(arg: Buffer<Double>): DoubleBuffer {
+        require(arg.size == size) { "The buffer size ${arg.size} does not match context size $size" }
+        return RealBufferFieldOperations.cos(arg)
+    }
+
+    override fun power(arg: Buffer<Double>, pow: Number): DoubleBuffer {
+        require(arg.size == size) { "The buffer size ${arg.size} does not match context size $size" }
+        return RealBufferFieldOperations.power(arg, pow)
+    }
+
+    override fun exp(arg: Buffer<Double>): DoubleBuffer {
+        require(arg.size == size) { "The buffer size ${arg.size} does not match context size $size" }
+        return RealBufferFieldOperations.exp(arg)
+    }
+
+    override fun ln(arg: Buffer<Double>): DoubleBuffer {
+        require(arg.size == size) { "The buffer size ${arg.size} does not match context size $size" }
+        return RealBufferFieldOperations.ln(arg)
+    }
+
 }

kmath-histograms/src/commonMain/kotlin/scientifik/kmath/histogram/Counters.kt

@@ -2,9 +2,9 @@ package scientifik.kmath.histogram
 
 /*
  * Common representation for atomic counters
+ * TODO replace with atomics
  */
 
-
 expect class LongCounter() {
     fun decrement()
     fun increment()

kmath-histograms/src/commonMain/kotlin/scientifik/kmath/histogram/Histogram.kt

@@ -2,12 +2,8 @@ package scientifik.kmath.histogram
 
 import scientifik.kmath.linear.Point
 import scientifik.kmath.structures.ArrayBuffer
-import scientifik.kmath.structures.Buffer
 import scientifik.kmath.structures.DoubleBuffer
 
-
-typealias RealPoint = Buffer<Double>
-
 /**
  * A simple geometric domain
  * TODO move to geometry module
@@ -42,13 +38,14 @@ interface Histogram<T : Any, out B : Bin<T>> : Iterable<B> {
 
 }
 
-interface MutableHistogram<T : Any, out B : Bin<T>> :
+interface MutableHistogram<T : Any, out B : Bin<T>> : Histogram<T, B> {
-    Histogram<T, B> {
 
     /**
      * Increment appropriate bin
      */
-    fun put(point: Point<out T>, weight: Double = 1.0)
+    fun putWithWeight(point: Point<out T>, weight: Double)
+
+    fun put(point: Point<out T>) = putWithWeight(point, 1.0)
 }
 
 fun <T : Any> MutableHistogram<T, *>.put(vararg point: T) = put(ArrayBuffer(point))

kmath-histograms/src/commonMain/kotlin/scientifik/kmath/histogram/PhantomHistogram.kt

@@ -1,64 +0,0 @@
-package scientifik.kmath.histogram
-
-import scientifik.kmath.linear.Point
-import scientifik.kmath.linear.Vector
-import scientifik.kmath.operations.Space
-import scientifik.kmath.structures.NDStructure
-import scientifik.kmath.structures.asSequence
-
-data class BinTemplate<T : Comparable<T>>(val center: Vector<T, *>, val sizes: Point<T>) {
-    fun contains(vector: Point<out T>): Boolean {
-        if (vector.size != center.size) error("Dimension mismatch for input vector. Expected ${center.size}, but found ${vector.size}")
-        val upper = center.context.run { center + sizes / 2.0 }
-        val lower = center.context.run { center - sizes / 2.0 }
-        return vector.asSequence().mapIndexed { i, value ->
-            value in lower[i]..upper[i]
-        }.all { it }
-    }
-}
-
-/**
- * A space to perform arithmetic operations on histograms
- */
-interface HistogramSpace<T : Any, B : Bin<T>, H : Histogram<T, B>> : Space<H> {
-    /**
-     * Rules for performing operations on bins
-     */
-    val binSpace: Space<Bin<T>>
-}
-
-class PhantomBin<T : Comparable<T>>(val template: BinTemplate<T>, override val value: Number) :
-    Bin<T> {
-
-    override fun contains(vector: Point<out T>): Boolean = template.contains(vector)
-
-    override val dimension: Int
-        get() = template.center.size
-
-    override val center: Point<T>
-        get() = template.center
-
-}
-
-/**
- * Immutable histogram with explicit structure for content and additional external bin description.
- * Bin search is slow, but full histogram algebra is supported.
- * @param bins transform a template into structure index
- */
-class PhantomHistogram<T : Comparable<T>>(
-    val bins: Map<BinTemplate<T>, IntArray>,
-    val data: NDStructure<Number>
-) : Histogram<T, PhantomBin<T>> {
-
-    override val dimension: Int
-        get() = data.dimension
-
-    override fun iterator(): Iterator<PhantomBin<T>> =
-            bins.asSequence().map { entry -> PhantomBin(entry.key, data[entry.value]) }.iterator()
-
-    override fun get(point: Point<out T>): PhantomBin<T>? {
-        val template = bins.keys.find { it.contains(point) }
-        return template?.let { PhantomBin(it, data[bins[it]!!]) }
-    }
-
-}

kmath-histograms/src/commonMain/kotlin/scientifik/kmath/histogram/RealHistogram.kt

@@ -1,45 +1,66 @@
 package scientifik.kmath.histogram
 
+import scientifik.kmath.linear.Point
 import scientifik.kmath.linear.toVector
+import scientifik.kmath.operations.SpaceOperations
 import scientifik.kmath.structures.*
 import kotlin.math.floor
 
-private operator fun RealPoint.minus(other: RealPoint) = ListBuffer((0 until size).map { get(it) - other[it] })
 
-private inline fun <T> Buffer<out Double>.mapIndexed(crossinline mapper: (Int, Double) -> T): Sequence<T> =
+data class BinDef<T : Comparable<T>>(val space: SpaceOperations<Point<T>>, val center: Point<T>, val sizes: Point<T>) {
-    (0 until size).asSequence().map { mapper(it, get(it)) }
+    fun contains(vector: Point<out T>): Boolean {
+        if (vector.size != center.size) error("Dimension mismatch for input vector. Expected ${center.size}, but found ${vector.size}")
+        val upper = space.run { center + sizes / 2.0 }
+        val lower = space.run { center - sizes / 2.0 }
+        return vector.asSequence().mapIndexed { i, value ->
+            value in lower[i]..upper[i]
+        }.all { it }
+    }
+}
+
+
+class MultivariateBin<T : Comparable<T>>(val def: BinDef<T>, override val value: Number) : Bin<T> {
+
+    override fun contains(vector: Point<out T>): Boolean = def.contains(vector)
+
+    override val dimension: Int
+        get() = def.center.size
+
+    override val center: Point<T>
+        get() = def.center
+
+}
 
 /**
  * Uniform multivariate histogram with fixed borders. Based on NDStructure implementation with complexity of m for bin search, where m is the number of dimensions.
  */
-class FastHistogram(
+class RealHistogram(
-    private val lower: RealPoint,
+    private val lower: Buffer<Double>,
-    private val upper: RealPoint,
+    private val upper: Buffer<Double>,
     private val binNums: IntArray = IntArray(lower.size) { 20 }
-) : MutableHistogram<Double, PhantomBin<Double>> {
+) : MutableHistogram<Double, MultivariateBin<Double>> {
 
 
     private val strides = DefaultStrides(IntArray(binNums.size) { binNums[it] + 2 })
 
-    private val values: NDStructure<LongCounter> = inlineNDStructure(strides) { LongCounter() }
+    private val values: NDStructure<LongCounter> = NDStructure.auto(strides) { LongCounter() }
 
     //private val weight: NDStructure<DoubleCounter?> = ndStructure(strides){null}
 
-    //TODO optimize binSize performance if needed
+
-    private val binSize: RealPoint =
+    override val dimension: Int get() = lower.size
-        ListBuffer((upper - lower).mapIndexed { index, value -> value / binNums[index] }.toList())
+
+
+    private val binSize = DoubleBuffer(dimension) { (upper[it] - lower[it]) / binNums[it] }
 
     init {
         // argument checks
         if (lower.size != upper.size) error("Dimension mismatch in histogram lower and upper limits.")
         if (lower.size != binNums.size) error("Dimension mismatch in bin count.")
-        if ((upper - lower).asSequence().any { it <= 0 }) error("Range for one of axis is not strictly positive")
+        if ((0 until dimension).any { upper[it] - lower[it] < 0 }) error("Range for one of axis is not strictly positive")
     }
 
 
-    override val dimension: Int get() = lower.size
-
-
     /**
      * Get internal [NDStructure] bin index for given axis
      */
@@ -61,49 +82,41 @@ class FastHistogram(
         return getValue(getIndex(point))
     }
 
-    private fun getTemplate(index: IntArray): BinTemplate<Double> {
+    private fun getDef(index: IntArray): BinDef<Double> {
         val center = index.mapIndexed { axis, i ->
             when (i) {
                 0 -> Double.NEGATIVE_INFINITY
                 strides.shape[axis] - 1 -> Double.POSITIVE_INFINITY
                 else -> lower[axis] + (i.toDouble() - 0.5) * binSize[axis]
             }
-        }.toVector()
+        }.asBuffer()
-        return BinTemplate(center, binSize)
+        return BinDef(RealBufferFieldOperations, center, binSize)
     }
 
-    fun getTemplate(point: Buffer<out Double>): BinTemplate<Double> {
+    fun getDef(point: Buffer<out Double>): BinDef<Double> {
-        return getTemplate(getIndex(point))
+        return getDef(getIndex(point))
     }
 
-    override fun get(point: Buffer<out Double>): PhantomBin<Double>? {
+    override fun get(point: Buffer<out Double>): MultivariateBin<Double>? {
         val index = getIndex(point)
-        return PhantomBin(getTemplate(index), getValue(index))
+        return MultivariateBin(getDef(index), getValue(index))
     }
 
-    override fun put(point: Buffer<out Double>, weight: Double) {
+    override fun putWithWeight(point: Buffer<out Double>, weight: Double) {
         if (weight != 1.0) TODO("Implement weighting")
         val index = getIndex(point)
         values[index].increment()
     }
 
-    override fun iterator(): Iterator<PhantomBin<Double>> = values.elements().map { (index, value) ->
+    override fun iterator(): Iterator<MultivariateBin<Double>> = values.elements().map { (index, value) ->
-        PhantomBin(getTemplate(index), value.sum())
+        MultivariateBin(getDef(index), value.sum())
     }.iterator()
 
     /**
      * Convert this histogram into NDStructure containing bin values but not bin descriptions
      */
     fun asNDStructure(): NDStructure<Number> {
-        return inlineNdStructure(this.values.shape) { values[it].sum() }
+        return NDStructure.auto(this.values.shape) { values[it].sum() }
-    }
-
-    /**
-     * Create a phantom lightweight immutable copy of this histogram
-     */
-    fun asPhantomHistogram(): PhantomHistogram<Double> {
-        val binTemplates = values.elements().associate { (index, _) -> getTemplate(index) to index }
-        return PhantomHistogram(binTemplates, asNDStructure())
     }
 
     companion object {
@@ -117,8 +130,8 @@ class FastHistogram(
          *)
          *```
          */
-        fun fromRanges(vararg ranges: ClosedFloatingPointRange<Double>): FastHistogram {
+        fun fromRanges(vararg ranges: ClosedFloatingPointRange<Double>): RealHistogram {
-            return FastHistogram(
+            return RealHistogram(
                 ranges.map { it.start }.toVector(),
                 ranges.map { it.endInclusive }.toVector()
             )
@@ -133,8 +146,8 @@ class FastHistogram(
          *)
          *```
          */
-        fun fromRanges(vararg ranges: Pair<ClosedFloatingPointRange<Double>, Int>): FastHistogram {
+        fun fromRanges(vararg ranges: Pair<ClosedFloatingPointRange<Double>, Int>): RealHistogram {
-            return FastHistogram(
+            return RealHistogram(
                 ListBuffer(ranges.map { it.first.start }),
                 ListBuffer(ranges.map { it.first.endInclusive }),
                 ranges.map { it.second }.toIntArray()

kmath-histograms/src/commonTest/kotlin/scietifik/kmath/histogram/MultivariateHistogramTest.kt

@@ -1,6 +1,6 @@
 package scietifik.kmath.histogram
 
-import scientifik.kmath.histogram.FastHistogram
+import scientifik.kmath.histogram.RealHistogram
 import scientifik.kmath.histogram.fill
 import scientifik.kmath.histogram.put
 import scientifik.kmath.linear.Vector
@@ -13,7 +13,7 @@ import kotlin.test.assertTrue
 class MultivariateHistogramTest {
     @Test
     fun testSinglePutHistogram() {
-        val histogram = FastHistogram.fromRanges(
+        val histogram = RealHistogram.fromRanges(
             (-1.0..1.0),
             (-1.0..1.0)
         )
@@ -26,7 +26,7 @@ class MultivariateHistogramTest {
 
     @Test
     fun testSequentialPut() {
-        val histogram = FastHistogram.fromRanges(
+        val histogram = RealHistogram.fromRanges(
             (-1.0..1.0),
             (-1.0..1.0),
             (-1.0..1.0)

kmath-histograms/src/jvmMain/kotlin/scientifik/kmath/histogram/UnivariateHistogram.kt

@@ -59,7 +59,7 @@ class UnivariateHistogram private constructor(private val factory: (Double) -> U
         (get(value) ?: createBin(value)).inc()
     }
 
-    override fun put(point: Buffer<out Double>, weight: Double) {
+    override fun putWithWeight(point: Buffer<out Double>, weight: Double) {
         if (weight != 1.0) TODO("Implement weighting")
         put(point[0])
     }