Add field test, minor refactor

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

@@ -59,7 +59,7 @@ public object ComplexField : ExtendedField<Complex>, Norm<Complex, Complex> {
     public override fun divide(a: Complex, b: Complex): Complex = when {
         b.re.isNaN() || b.im.isNaN() -> Complex(Double.NaN, Double.NaN)
 
-        (if (b.im < 0) -b.im else +b.im) < (if (b.re < 0) -b.re else +b.re) -> {
+        abs(b.im) < abs(b.re) -> {
             val wr = b.im / b.re
             val wd = b.re + wr * b.im
 
@@ -91,8 +91,8 @@ public object ComplexField : ExtendedField<Complex>, Norm<Complex, Complex> {
         return i * (e1 - e2) / (e1 + e2)
     }
 
-    public override fun asin(arg: Complex): Complex = -i * ln(sqrt(1 - (arg * arg)) + i * arg)
+    public override fun asin(arg: Complex): Complex = -i * ln(sqrt(one - (arg * arg)) + i * arg)
-    public override fun acos(arg: Complex): Complex = PI_DIV_2 + i * ln(sqrt(1 - (arg * arg)) + i * arg)
+    public override fun acos(arg: Complex): Complex = PI_DIV_2 + i * ln(sqrt(one - (arg * arg)) + i * arg)
 
     public override fun atan(arg: Complex): Complex {
         val iArg = i * arg
@@ -125,6 +125,7 @@ public object ComplexField : ExtendedField<Complex>, Norm<Complex, Complex> {
 public data class Complex(val re: Double, val im: Double) : FieldElement<Complex, Complex, ComplexField>,
     Comparable<Complex> {
     public constructor(re: Number, im: Number) : this(re.toDouble(), im.toDouble())
+    public constructor(re: Number) : this(re.toDouble(), 0.0)
 
     public override val context: ComplexField
         get() = ComplexField
@@ -155,7 +156,7 @@ public data class Complex(val re: Double, val im: Double) : FieldElement<Complex
  * @receiver the real part.
  * @return the new complex number.
  */
-public fun Number.toComplex(): Complex = Complex(this, 0)
+public fun Number.toComplex(): Complex = Complex(this)
 
 /**
  * Creates a new buffer of complex numbers with the specified [size], where each element is calculated by calling the

kmath-core/src/commonMain/kotlin/kscience/kmath/operations/Quaternion.kt

@@ -85,20 +85,23 @@ public object QuaternionField : Field<Quaternion>, Norm<Quaternion, Quaternion>,
         return exp(pow * ln(arg))
     }
 
-    private fun pwr(x: Quaternion, a: Int): Quaternion {
+    private fun pwr(x: Quaternion, a: Int): Quaternion = when {
-        if (a < 0) return -(pwr(x, -a))
+        a < 0 -> -(pwr(x, -a))
-        if (a == 0) return one
+        a == 0 -> one
-        if (a == 1) return x
+        a == 1 -> x
-        if (a == 2) return pwr2(x)
+        a == 2 -> pwr2(x)
-        if (a == 3) return pwr3(x)
+        a == 3 -> pwr3(x)
-        if (a == 4) return pwr4(x)
+        a == 4 -> pwr4(x)
+
+        else -> {
             val x4 = pwr4(x)
             var y = x4
             repeat((1 until a / 4).count()) { y *= x4 }
             if (a % 4 == 3) y *= pwr3(x)
             if (a % 4 == 2) y *= pwr2(x)
             if (a % 4 == 1) y *= x
-        return y
+            y
+        }
     }
 
     private inline fun pwr2(x: Quaternion): Quaternion {
@@ -204,7 +207,11 @@ public data class Quaternion(val w: Double, val x: Double, val y: Double, val z:
         z.toDouble()
     )
 
+    public constructor(w: Number, x: Number, y: Number) : this(w.toDouble(), x.toDouble(), y.toDouble(), 0.0)
+    public constructor(w: Number, x: Number) : this(w.toDouble(), x.toDouble(), 0.0, 0.0)
+    public constructor(w: Number) : this(w.toDouble(), 0.0, 0.0, 0.0)
     public constructor(wx: Complex, yz: Complex) : this(wx.re, wx.im, yz.re, yz.im)
+    public constructor(wx: Complex) : this(wx.re, wx.im, 0, 0)
 
     public override val context: QuaternionField
         get() = QuaternionField
@@ -241,7 +248,7 @@ public data class Quaternion(val w: Double, val x: Double, val y: Double, val z:
  * @receiver the real part.
  * @return a new quaternion.
  */
-public fun Number.toQuaternion(): Quaternion = Quaternion(this, 0, 0, 0)
+public fun Number.toQuaternion(): Quaternion = Quaternion(this)
 
 /**
  * Creates a quaternion with `w`-component equal to `re`-component of given complex and `x`-component equal to
@@ -250,7 +257,7 @@ public fun Number.toQuaternion(): Quaternion = Quaternion(this, 0, 0, 0)
  * @receiver the complex number.
  * @return a new quaternion.
  */
-public fun Complex.toQuaternion(): Quaternion = Quaternion(re, im, 0, 0)
+public fun Complex.toQuaternion(): Quaternion = Quaternion(this)
 
 /**
  * Creates a new buffer of quaternions with the specified [size], where each element is calculated by calling the

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

@@ -1,39 +1,30 @@
 package kscience.kmath.operations
 
+import kotlin.math.sqrt
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertTrue
 
 internal class ComplexTest {
     @Test
-    fun conjugate() {
+    fun conjugate() = assertEquals(Complex(0, -42), (ComplexField.i * 42).conjugate)
-        assertEquals(
-            Complex(0, -42), (ComplexField.i * 42).conjugate
-        )
-    }
 
     @Test
-    fun reciprocal() {
+    fun reciprocal() = assertTrue((Complex(0.5, -0.0) - 2.toComplex().reciprocal).r < 1e-10)
-        assertTrue { (Complex(0.5, -0.0) - 2.toComplex().reciprocal).r < 1e-10}
-    }
 
     @Test
-    fun r() {
+    fun r() = assertEquals(sqrt(2.0), (ComplexField.i + 1.0.toComplex()).r)
-        assertEquals(kotlin.math.sqrt(2.0), (ComplexField.i + 1.0.toComplex()).r)
-    }
 
     @Test
-    fun theta() {
+    fun theta() = assertEquals(0.0, 1.toComplex().theta)
-        assertEquals(0.0, 1.toComplex().theta)
-    }
 
     @Test
     fun toComplex() {
-        assertEquals(Complex(42, 0), 42.toComplex())
+        assertEquals(Complex(42), 42.toComplex())
-        assertEquals(Complex(42.0, 0), 42.0.toComplex())
+        assertEquals(Complex(42.0), 42.0.toComplex())
-        assertEquals(Complex(42f, 0), 42f.toComplex())
+        assertEquals(Complex(42f), 42f.toComplex())
-        assertEquals(Complex(42.0, 0), 42.0.toComplex())
+        assertEquals(Complex(42.0), 42.0.toComplex())
-        assertEquals(Complex(42.toByte(), 0), 42.toByte().toComplex())
+        assertEquals(Complex(42.toByte()), 42.toByte().toComplex())
-        assertEquals(Complex(42.toShort(), 0), 42.toShort().toComplex())
+        assertEquals(Complex(42.toShort()), 42.toShort().toComplex())
     }
 }

kmath-core/src/commonTest/kotlin/kscience/kmath/operations/QuaternionFieldTest.kt

@@ -0,0 +1,50 @@
+package kscience.kmath.operations
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+internal class QuaternionFieldTest {
+    @Test
+    fun testAddition() {
+        assertEquals(Quaternion(42, 42), QuaternionField { Quaternion(16, 16) + Quaternion(26, 26) })
+        assertEquals(Quaternion(42, 16), QuaternionField { Quaternion(16, 16) + 26 })
+        assertEquals(Quaternion(42, 16), QuaternionField { 26 + Quaternion(16, 16) })
+    }
+
+    @Test
+    fun testSubtraction() {
+        assertEquals(Quaternion(42, 42), QuaternionField { Quaternion(86, 55) - Quaternion(44, 13) })
+        assertEquals(Quaternion(42, 56), QuaternionField { Quaternion(86, 56) - 44 })
+        assertTrue(Quaternion(42, 56) - QuaternionField { 86 - Quaternion(44, -56) } < 1e-10.toQuaternion())
+    }
+
+    @Test
+    fun testMultiplication() {
+        assertEquals(Quaternion(42, 42), QuaternionField { Quaternion(4.2, 0) * Quaternion(10, 10) })
+        assertEquals(Quaternion(42, 21), QuaternionField { Quaternion(4.2, 2.1) * 10 })
+        assertEquals(Quaternion(42, 21), QuaternionField { 10 * Quaternion(4.2, 2.1) })
+    }
+
+    @Test
+    fun testDivision() {
+        assertEquals(Quaternion(42, 42), QuaternionField { Quaternion(0, 168) / Quaternion(2, 2) })
+        assertEquals(Quaternion(42, 56), QuaternionField { Quaternion(86, 56) - 44 })
+        assertTrue(Quaternion(42, 56) - QuaternionField { 86 - Quaternion(44, -56) } < 1e-10.toQuaternion())
+    }
+
+    @Test
+    fun testPower() {
+        assertEquals(QuaternionField.zero, QuaternionField { zero pow 2 })
+        assertEquals(QuaternionField.zero, QuaternionField { zero pow 2 })
+
+        assertEquals(
+            QuaternionField { i * 8 }.let { it.x.toInt() to it.w.toInt() },
+            QuaternionField { Quaternion(2, 2) pow 2 }.let { it.x.toInt() to it.w.toInt() })
+    }
+
+    @Test
+    fun testNorm() {
+        assertEquals(2.toQuaternion(), QuaternionField { norm(2 * i) })
+    }
+}