Add alpha back to link, just in case

src/link.js

@@ -3,15 +3,10 @@ import jiggle from "./jiggle";
 
 /**
  * Modified link force algorithm
- * - ignore alpha
- * - removed bias
- * - modified strength calculation
+ * - simplify calculations for parameters locked for spring model
  * - removed other unused functions
- * Making it more suitable for the spring model.
- * This should initialize and perform calculation a bit faster, and also
- * use a bit less memory
+ * Alpha should be constant 1 for accurate simulation
  */
-
 export default function(links) {
   var dataSizeFactor,
       distance = constant(30),
@@ -21,9 +16,11 @@ export default function(links) {
 
   if (links == null) links = [];
 
-  function force() {
-    for (var k = 0, n = links.length; k < iterations; ++k) { // Each iteration in a tick
-      for (var i = 0, link, source, target, x, y, l, b; i < n; ++i) { // For each link
+  function force(alpha) {
+    // Each iteration in a tick
+    for (var k = 0, n = links.length; k < iterations; ++k) {
+      // For each link
+      for (var i = 0, link, source, target, x, y, l, b; i < n; ++i) {
         link = links[i];
         // jiggle so it wont divide / multiply by zero after this
         source = link.source;
@@ -31,7 +28,7 @@ export default function(links) {
         x = target.x + target.vx - source.x - source.vx || jiggle();
         y = target.y + target.vy - source.y - source.vy || jiggle();
         l = Math.sqrt(x * x + y * y);
-        l = (l - distances[i]) / l  * dataSizeFactor;
+        l = (l - distances[i]) / l  * dataSizeFactor * alpha;
         x *= l, y *= l;
         target.vx -= x;
         target.vy -= y;
@@ -49,7 +46,6 @@ export default function(links) {
 
   function initializeDistance() {
     if (!nodes) return;
-
     for (var i = 0, n = links.length; i < n; ++i) {
       distances[i] = +distance(links[i], i, links);
     }