Data commit

Task/Euler-method/Kotlin/euler-method.kotlin

@@ -0,0 +1,32 @@
+// version 1.1.2
+
+typealias Deriv = (Double) -> Double  // only one parameter needed here
+
+const val FMT = " %7.3f"
+
+fun euler(f: Deriv, y: Double, step: Int, end: Int) {
+    var yy = y
+    print(" Step %2d: ".format(step))
+    for (t in 0..end step step) {
+        if (t % 10 == 0) print(FMT.format(yy))
+        yy += step * f(yy)
+    }
+    println()
+}
+
+fun analytic() {
+    print("    Time: ")
+    for (t in 0..100 step 10) print(" %7d".format(t))
+    print("\nAnalytic: ")
+    for (t in 0..100 step 10)
+        print(FMT.format(20.0 + 80.0 * Math.exp(-0.07 * t)))
+    println()
+}
+
+fun cooling(temp: Double) = -0.07 * (temp - 20.0)
+
+fun main(args: Array<String>) {
+    analytic()
+    for (i in listOf(2, 5, 10))
+        euler(::cooling, 100.0, i, 100)
+}