Adding Forward Euler in Swift (algorithm-archivists#255)

Author: Wesley-Arrington

contents/forward_euler_method/code/swift/euler.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+func solveEuler(timeStep: Double, n: Int) -> [Double] {
+    var result : [Double] = [1]
+
+    for i in 1...n {
+        result.append(result[i - 1] - 3 * result[i - 1] * timeStep)
+    }
+    return result
+}
+
+func checkResult(result: [Double], threshold: Double, timeStep: Double) -> Bool {
+    var isApprox = true
+    
+    for i in 0..<result.count {
+        let solution = exp(-3 * Double(i) * timeStep)
+        if abs(result[i] - solution) > threshold {
+            print(result[i], solution)
+            isApprox = false
+        }
+    }
+    return isApprox
+}
+
+func main() {
+    let timeStep = 0.01
+    let n = 100
+    let threshold = 0.01
+
+    let result = solveEuler(timeStep: timeStep, n: n)
+    let isApprox = checkResult(result: result, threshold: threshold, timeStep: timeStep)
+
+    if isApprox {
+        print("All values within threshold")
+    } else {
+        print("Value(s) not in threshold")
+    }
+}
+
+main()

contents/forward_euler_method/forward_euler_method.md

@@ -119,6 +119,8 @@ Full code for the visualization follows:
 [import, lang:"haskell"](code/haskell/euler.hs)
 {% sample lang="m" %}
 [import, lang:"matlab"](code/matlab/euler.m)
+{% sample lang="swift" %}
+[import, lang:"swift"](code/swift/euler.swift)
 {% endmethod %}
 
 <script>