June 2018 Update

Task/Element-wise-operations/Kotlin/element-wise-operations.kotlin

@@ -0,0 +1,48 @@
+// version 1.1.51
+
+typealias Matrix = Array<DoubleArray>
+typealias Op = Double.(Double) -> Double
+
+fun Double.dPow(exp: Double) = Math.pow(this, exp)
+
+fun Matrix.elementwiseOp(other: Matrix, op: Op): Matrix {
+    require(this.size == other.size && this[0].size == other[0].size)
+    val result = Array(this.size) { DoubleArray(this[0].size) }
+    for (i in 0 until this.size) {
+        for (j in 0 until this[0].size) result[i][j] = this[i][j].op(other[i][j])
+    }
+    return result
+}
+
+fun Matrix.elementwiseOp(d: Double, op: Op): Matrix {
+    val result = Array(this.size) { DoubleArray(this[0].size) }
+    for (i in 0 until this.size) {
+        for (j in 0 until this[0].size) result[i][j] = this[i][j].op(d)
+    }
+    return result
+}
+
+fun Matrix.print(name: Char?, scalar: Boolean? = false) {
+    println(when (scalar) {
+        true  -> "m $name s"
+        false -> "m $name m"
+        else  -> "m"
+    } + ":")
+    for (i in 0 until this.size) println(this[i].asList())
+    println()
+}
+
+fun main(args: Array<String>) {
+    val ops = listOf(Double::plus, Double::minus, Double::times, Double::div, Double::dPow)
+    val names = "+-*/^"
+    val m = arrayOf(
+        doubleArrayOf(3.0, 5.0, 7.0),
+        doubleArrayOf(1.0, 2.0, 3.0),
+        doubleArrayOf(2.0, 4.0, 6.0)
+    )
+    m.print(null, null)
+    for ((i, op) in ops.withIndex()) m.elementwiseOp(m, op).print(names[i])
+    val s = 2.0
+    println("s = $s:\n")
+    for ((i, op) in ops.withIndex()) m.elementwiseOp(s, op).print(names[i], true)
+}