Merge remote-tracking branch 'origin/dev' into hyp-trig-functions

# Conflicts:
#	kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Algebra.kt
#	kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Complex.kt
#	kmath-core/src/commonTest/kotlin/scientifik/kmath/operations/ComplexFieldTest.kt

CHANGELOG.md

@@ -0,0 +1,32 @@
+# KMath
+
+## [Unreleased]
+
+### Added
+- Functional Expressions API
+- Mathematical Syntax Tree, its interpreter and API
+- String to MST parser (https://github.com/mipt-npm/kmath/pull/120)
+- MST to JVM bytecode translator (https://github.com/mipt-npm/kmath/pull/94)
+- FloatBuffer (specialized MutableBuffer over FloatArray)
+- FlaggedBuffer to associate primitive numbers buffer with flags (to mark values infinite or missing, etc.)
+- Specialized builder functions for all primitive buffers like `IntBuffer(25) { it + 1 }` (https://github.com/mipt-npm/kmath/pull/125)
+- Interface `NumericAlgebra` where `number` operation is available to convert numbers to algebraic elements
+- Inverse trigonometric functions support in ExtendedField (`asin`, `acos`, `atan`) (https://github.com/mipt-npm/kmath/pull/114)
+- New space extensions: `average` and `averageWith`
+- Local coding conventions
+- Geometric Domains API in `kmath-core`
+- Blocking chains in `kmath-coroutines`
+
+### Changed
+- BigInteger and BigDecimal algebra: JBigDecimalField has companion object with default math context; minor optimizations
+- `power(T, Int)` extension function has preconditions and supports `Field<T>`
+- Memory objects have more preconditions (overflow checking)
+- `tg` function is renamed to `tan` (https://github.com/mipt-npm/kmath/pull/114)
+- Gradle version: 6.3 -> 6.5.1
+- Moved probability distributions to commons-rng and to `kmath-prob`.
+
+### Fixed
+- Missing copy method in Memory implementation on JS (https://github.com/mipt-npm/kmath/pull/106)
+- D3.dim value in `kmath-dimensions`
+- Multiplication in integer rings in `kmath-core` (https://github.com/mipt-npm/kmath/pull/101)
+- Commons RNG compatibility (https://github.com/mipt-npm/kmath/issues/93)

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

@@ -61,7 +61,7 @@ inline operator fun <A : Algebra<*>, R> A.invoke(block: A.() -> R): R = run(bloc
  * Represents "semispace", i.e. algebraic structure with associative binary operation called "addition" as well as
  * multiplication by scalars.
  *
- * @param T the type of element of this "semispace".
+ * @param T the type of element of this semispace.
  */
 interface SpaceOperations<T> : Algebra<T> {
     /**

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

@@ -4,7 +4,7 @@ package scientifik.kmath.operations
  * Returns the sum of all elements in the iterable in this [Space].
  *
  * @receiver the algebra that provides addition.
- * @param data the collection to sum up.
+ * @param data the iterable to sum up.
  * @return the sum.
  */
 fun <T> Space<T>.sum(data: Iterable<T>): T = data.fold(zero) { left, right -> add(left, right) }
@@ -13,11 +13,29 @@ fun <T> Space<T>.sum(data: Iterable<T>): T = data.fold(zero) { left, right -> ad
  * Returns the sum of all elements in the sequence in this [Space].
  *
  * @receiver the algebra that provides addition.
- * @param data the collection to sum up.
+ * @param data the sequence to sum up.
  * @return the sum.
  */
 fun <T> Space<T>.sum(data: Sequence<T>): T = data.fold(zero) { left, right -> add(left, right) }
 
+/**
+ * Returns an average value of elements in the iterable in this [Space].
+ *
+ * @receiver the algebra that provides addition and division.
+ * @param data the iterable to find average.
+ * @return the average value.
+ */
+fun <T> Space<T>.average(data: Iterable<T>): T = sum(data) / data.count()
+
+/**
+ * Returns an average value of elements in the sequence in this [Space].
+ *
+ * @receiver the algebra that provides addition and division.
+ * @param data the sequence to find average.
+ * @return the average value.
+ */
+fun <T> Space<T>.average(data: Sequence<T>): T = sum(data) / data.count()
+
 /**
  * Returns the sum of all elements in the iterable in provided space.
  *
@@ -25,7 +43,34 @@ fun <T> Space<T>.sum(data: Sequence<T>): T = data.fold(zero) { left, right -> ad
  * @param space the algebra that provides addition.
  * @return the sum.
  */
-fun <T : Any, S : Space<T>> Iterable<T>.sumWith(space: S): T = space.sum(this)
+fun <T> Iterable<T>.sumWith(space: Space<T>): T = space.sum(this)
+
+/**
+ * Returns the sum of all elements in the sequence in provided space.
+ *
+ * @receiver the collection to sum up.
+ * @param space the algebra that provides addition.
+ * @return the sum.
+ */
+fun <T> Sequence<T>.sumWith(space: Space<T>): T = space.sum(this)
+
+/**
+ * Returns an average value of elements in the iterable in this [Space].
+ *
+ * @receiver the iterable to find average.
+ * @param space the algebra that provides addition and division.
+ * @return the average value.
+ */
+fun <T> Iterable<T>.averageWith(space: Space<T>): T = space.average(this)
+
+/**
+ * Returns an average value of elements in the sequence in this [Space].
+ *
+ * @receiver the sequence to find average.
+ * @param space the algebra that provides addition and division.
+ * @return the average value.
+ */
+fun <T> Sequence<T>.averageWith(space: Space<T>): T = space.average(this)
 
 //TODO optimized power operation
 

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

@@ -40,7 +40,7 @@ private val PI_DIV_2 = Complex(PI / 2, 0)
 /**
  * A field of [Complex].
  */
-object ComplexField : ExtendedField<Complex> {
+object ComplexField : ExtendedField<Complex>, Norm<Complex, Complex> {
     override val zero: Complex = 0.0.toComplex()
     override val one: Complex = 1.0.toComplex()
 
@@ -153,6 +153,8 @@ object ComplexField : ExtendedField<Complex> {
      */
     operator fun Double.times(c: Complex): Complex = Complex(c.re * this, c.im * this)
 
+    override fun norm(arg: Complex): Complex = arg.conjugate * arg
+
     override fun symbol(value: String): Complex = if (value == "i") i else super.symbol(value)
 }
 

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

@@ -1,7 +1,7 @@
 package scientifik.kmath.structures
 
 /**
- * Specialized [MutableBuffer] implementation over [ShortBuffer].
+ * Specialized [MutableBuffer] implementation over [ShortArray].
  *
  * @property array the underlying array.
  */

kmath-core/src/commonTest/kotlin/scientifik/kmath/operations/ComplexTest.kt

@@ -0,0 +1,38 @@
+package scientifik.kmath.operations
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+internal class ComplexTest {
+    @Test
+    fun conjugate() {
+        assertEquals(
+            Complex(0, -42), (ComplexField.i * 42).conjugate
+        )
+    }
+
+    @Test
+    fun reciprocal() {
+        assertEquals(Complex(0.5, -0.0), 2.toComplex().reciprocal)
+    }
+
+    @Test
+    fun r() {
+        assertEquals(kotlin.math.sqrt(2.0), (ComplexField.i + 1.0.toComplex()).r)
+    }
+
+    @Test
+    fun theta() {
+        assertEquals(0.0, 1.toComplex().theta)
+    }
+
+    @Test
+    fun toComplex() {
+        assertEquals(Complex(42, 0), 42.toComplex())
+        assertEquals(Complex(42.0, 0), 42.0.toComplex())
+        assertEquals(Complex(42f, 0), 42f.toComplex())
+        assertEquals(Complex(42.0, 0), 42.0.toComplex())
+        assertEquals(Complex(42.toByte(), 0), 42.toByte().toComplex())
+        assertEquals(Complex(42.toShort(), 0), 42.toShort().toComplex())
+    }
+}