Forward Euler in JavaScript (#418)

Author: depate

contents/forward_euler_method/code/javascript/euler.js

@@ -0,0 +1,31 @@
+function forwardEuler(timeStep, n) {
+  const arr = [1];
+  for (let i = 1; i <= n; i++) {
+    arr[i] = arr[i - 1] - 3 * arr[i - 1] * timeStep;
+  }
+  return arr;
+}
+
+function checkEuler(arr, timeStep, threshold) {
+  let isApprox = true;
+  arr.forEach((_value, i) => {
+    const solution = Math.exp(-3 * timeStep * i);
+
+    if (Math.abs(arr[i] - solution) > threshold) {
+      console.log(arr[i], solution);
+      isApprox = false;
+    }
+  });
+  return isApprox;
+}
+
+function main() {
+  const timeStep = 0.01;
+  const threshold = 0.01;
+  const n = 100;
+  const eulerResult = forwardEuler(timeStep, n);
+  const checkResult = checkEuler(eulerResult, timeStep, threshold);
+  console.log(checkResult);
+}
+
+main();

contents/forward_euler_method/forward_euler_method.md

@@ -122,6 +122,8 @@ Full code for the visualization follows:
 [import, lang:"matlab"](code/matlab/euler.m)
 {% sample lang="swift" %}
 [import, lang:"swift"](code/swift/euler.swift)
+{% sample lang="js" %}
+[import, lang:"javascript"](code/javascript/euler.js)
 {% sample lang="f90" %}
 [import, lang:"fortran"](code/fortran/euler.f90)
 {% sample lang="go" %}