Data commit

Task/Roots-of-a-function/JavaScript/roots-of-a-function.js

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+// This function notation is sorta new, but useful here
+// Part of the EcmaScript 6 Draft
+// developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions_and_function_scope
+var poly = (x => x*x*x - 3*x*x + 2*x);
+
+function sign(x) {
+	return (x < 0.0) ? -1 : (x > 0.0) ? 1 : 0;
+}
+
+function printRoots(f, lowerBound, upperBound, step) {
+	var  x = lowerBound, ox = x,
+		 y = f(x), oy = y,
+		 s = sign(y), os = s;
+
+	for (; x <= upperBound ; x += step) {
+	    s = sign(y = f(x));
+	    if (s == 0) {
+			console.log(x);
+	    }
+	    else if (s != os) {
+			var dx = x - ox;
+			var dy = y - oy;
+			var cx = x - dx * (y / dy);
+			console.log("~" + cx);
+	    }
+	    ox = x; oy = y; os = s;
+	}
+}
+
+printRoots(poly, -1.0, 4, 0.002);