Adding Verlet Integration in Swift (#263)

Author: Wesley-Arrington

contents/verlet_integration/code/swift/verlet.swift

@@ -0,0 +1,64 @@
+func verlet(pos: Double, acc: Double, dt: Double) -> Double {
+    var pos = pos
+    var temp_pos, time: Double
+    var prev_pos = pos
+    time = 0.0
+    
+    while (pos > 0) {
+        time += dt
+        temp_pos = pos
+        pos = pos*2 - prev_pos + acc * dt * dt
+        prev_pos = temp_pos
+    }
+    
+    return time
+}
+
+func stormerVerlet(pos: Double, acc: Double, dt: Double) -> (time: Double, vel: Double) {
+    var pos = pos
+    var temp_pos, time, vel: Double
+    var prev_pos = pos
+    vel = 0
+    time = 0
+    
+    while (pos > 0) {
+        time += dt
+        temp_pos = pos
+        pos = pos*2 - prev_pos + acc * dt * dt
+        prev_pos = temp_pos
+        
+        vel += acc*dt
+    }
+    
+    return (time:time, vel:vel)
+}
+
+func velocityVerlet(pos: Double, acc: Double, dt: Double) -> (time: Double, vel: Double) {
+    var pos = pos
+    var time, vel : Double
+    vel = 0
+    time = 0
+    
+    while (pos > 0) {
+        time += dt
+        pos += vel*dt + 0.5*acc * dt * dt
+        vel += acc*dt
+    }
+    
+    return (time:time, vel:vel)
+}
+
+func main() {
+    let verletTime = verlet(pos: 5.0, acc: -10.0, dt: 0.01)
+    print("Time for Verlet integration is: \(verletTime)")
+    
+    let stormer = stormerVerlet(pos: 5.0, acc: -10.0, dt: 0.01);
+    print("Time for Stormer Verlet integration is: \(stormer.time)")
+    print("Velocity for Stormer Verlet integration is: \(stormer.vel)")
+    
+    let velVerlet = velocityVerlet(pos: 5.0, acc: -10, dt: 0.01)
+    print("Time for velocity Verlet integration is: \(velVerlet.time)")
+    print("Velocity for velocity Verlet integration is: \(velVerlet.vel)")
+}
+
+main()

contents/verlet_integration/verlet_integration.md

@@ -56,6 +56,8 @@ Unfortunately, this has not yet been implemented in LabVIEW, so here's Julia cod
 [import:1-16, lang:"javascript"](code/javascript/verlet.js)
 {% sample lang="rs" %}
 [import:1-13, lang:"rust"](code/rust/verlet.rs)
+{% sample lang="swift" %}
+[import:1-15, lang:"swift"](code/swift/verlet.swift)
 {% endmethod %}
 
 
@@ -102,6 +104,8 @@ Unfortunately, this has not yet been implemented in LabVIEW, so here's Julia cod
 [import:18-35, lang:"javascript"](code/javascript/verlet.js)
 {% sample lang="rs" %}
 [import:15-27, lang:"rust"](code/rust/verlet.rs)
+{% sample lang="swift" %}
+[import:17-34, lang:"swift"](code/swift/verlet.swift)
 {% endmethod %}
 
 
@@ -159,6 +163,8 @@ Unfortunately, this has not yet been implemented in LabVIEW, so here's Julia cod
 [import:37-50, lang:"javascript"](code/javascript/verlet.js)
 {% sample lang="rs" %}
 [import:29-40, lang:"rust"](code/rust/verlet.rs)
+{% sample lang="swift" %}
+[import:36-49, lang:"swift"](code/swift/verlet.swift)
 {% endmethod %}
 
 
@@ -198,6 +204,8 @@ Submitted by P. Mekhail
 [import, lang:"javascript"](code/javascript/verlet.js)
 {% sample lang="rs" %}
 [import, lang:"rust"](code/rust/verlet.rs)
+{% sample lang="swift" %}
+[import, lang:"swift"](code/swift/verlet.swift)
 {% endmethod %}