all tasks

Task/Vector-products/JavaScript/vector-products.js

@@ -0,0 +1,70 @@
+function dotProduct() {
+  var len = arguments[0] && arguments[0].length;
+  var argsLen = arguments.length;
+  var i, j = len;
+  var prod, sum = 0;
+
+  // If no arguments supplied, return undefined
+  if (!len) {
+    return;
+  }
+
+  // If all vectors not same length, return undefined
+  i = argsLen;
+  while (i--) {
+
+    if (arguments[i].length != len) {
+      return;  // return undefined
+    }
+  }
+
+  // Sum terms
+  while (j--) {
+    i = argsLen;
+    prod = 1;
+
+    while (i--) {
+      prod *= arguments[i][j];
+    }
+    sum += prod;
+  }
+  return sum;
+}
+
+function crossProduct(a, b) {
+
+  // Check lengths
+  if (a.length != 3 || b.length != 3) {
+     return;
+  }
+
+  return [a[1]*b[2] - a[2]*b[1],
+          a[2]*b[0] - a[0]*b[2],
+          a[0]*b[1] - a[1]*b[0]];
+
+}
+
+function scalarTripleProduct(a, b, c) {
+  return dotProduct(a, crossProduct(b, c));
+}
+
+function vectorTripleProduct(a, b, c) {
+  return crossProduct(a, crossProduct(b, c));
+}
+
+// Run tests
+(function () {
+  var a = [3, 4, 5];
+  var b = [4, 3, 5];
+  var c = [-5, -12, -13];
+
+  alert(
+    'A . B: ' + dotProduct(a, b) +
+    '\n' +
+    'A x B: ' + crossProduct(a, b) +
+    '\n' +
+    'A . (B x C): ' + scalarTripleProduct(a, b, c) +
+    '\n' +
+    'A x (B x C): ' + vectorTripleProduct(a, b, c)
+  );
+}());