Data commit

Task/Euler-method/Swift/euler-method.swift

@@ -0,0 +1,42 @@
+import Foundation
+
+let numberFormat = " %7.3f"
+let k = 0.07
+let initialTemp = 100.0
+let finalTemp = 20.0
+let startTime = 0
+let endTime = 100
+
+func ivpEuler(function: (Double, Double) -> Double, initialValue: Double, step: Int) {
+    print(String(format: " Step %2d: ", step), terminator: "")
+    var y = initialValue
+    for t in stride(from: startTime, through: endTime, by: step) {
+        if t % 10 == 0 {
+            print(String(format: numberFormat, y), terminator: "")
+        }
+        y += Double(step) * function(Double(t), y)
+    }
+    print()
+}
+
+func analytic() {
+    print("    Time: ", terminator: "")
+    for t in stride(from: startTime, through: endTime, by: 10) {
+        print(String(format: " %7d", t), terminator: "")
+    }
+    print("\nAnalytic: ", terminator: "")
+    for t in stride(from: startTime, through: endTime, by: 10) {
+        let temp = finalTemp + (initialTemp - finalTemp) * exp(-k * Double(t))
+        print(String(format: numberFormat, temp), terminator: "")
+    }
+    print()
+}
+
+func cooling(t: Double, temp: Double) -> Double {
+    return -k * (temp - finalTemp)
+}
+
+analytic()
+ivpEuler(function: cooling, initialValue: initialTemp, step: 2)
+ivpEuler(function: cooling, initialValue: initialTemp, step: 5)
+ivpEuler(function: cooling, initialValue: initialTemp, step: 10)