Merge branch 'master' into withConsoleLog

src/link.js

@@ -15,6 +15,7 @@ export default function() {
       nodes,
       stableVelocity = 0,
       stableVeloHandler = null,
+      latestVelocityDiff = 0,
       iterations = 1;
 
   function force(alpha) {
@@ -54,6 +55,7 @@ export default function() {
         velocityDiff += Math.abs(Math.hypot(node.vx-node.oldvx, node.vy-node.oldvy));
       }
       velocityDiff /= n*(n-1);
+      latestVelocityDiff = velocityDiff;
 
       if(velocityDiff<stableVelocity){
         stableVeloHandler();
@@ -91,6 +93,10 @@ export default function() {
     return arguments.length ? (distance = typeof _ === "function" ? _ : constant(+_), initializeDistance(), force) : distance;
   };
 
+  force.latestAccel = function () {
+    return latestVelocityDiff;
+  };
+
   force.onStableVelo = function (_) {
     return arguments.length ? (stableVeloHandler = _, force) : stableVeloHandler;
   };

src/stress.js

@@ -6,8 +6,8 @@
   */
 export function getStress(nodes, distance) {
   let sumDiffSq = 0
-  let sumHighDistSq = 0;
-  for (let j = nodes.length-1; j >= 1; j++) {
+  let sumLowDDistSq = 0;
+  for (let j = nodes.length-1; j >= 1; j--) {
     for (let i = 0; i < j; i++) {
       let source = nodes[i], target = nodes[j];
       let lowDDist = Math.hypot(target.x - source.x, target.y - source.y);