为什么我在切换循环时会得到NaN

我试图在javascript中编写k-means函数。这是我的代码。

function kmeans(arrayToProcess,cluster_n){
    var pointDimension = arrayToProcess[0].length;
    var ClusterResult = new Array();
    var ClusterCenter = new Array();
    var oldClusterCenter = new Array();
    var changed=false;
    for(var i = 0;i<cluster_n;i++)
        ClusterCenter.push(arrayToProcess[randomInt(arrayToProcess.length-1)]);
    console.log(ClusterCenter);
    // do{
    for(var k=0;k<50;k++){//loop
        for(var i = 0; i<cluster_n; i++){
            ClusterResult[i] = new Array();
        }
        for(var i = 0; i<arrayToProcess.length; i++){
            //for every point element
            var oldDistance=-1;
            var newClusterNumber = 0;
            for(var j = 0; j<cluster_n; j++){
                //for every cluster
                var distance = Math.abs(computeDistanceBetween(arrayToProcess[i], ClusterCenter[j]));   
                if (oldDistance == -1){
                    oldDistance = distance;
                    newClusterNumber = j;
                }else if ( distance <= oldDistance ){
                    newClusterNumber = j;
                    oldDistance = distance;
                }
            }
            ClusterResult[newClusterNumber].push(arrayToProcess[i]);
        }
        oldClusterCenter = ClusterCenter;
        //compute new centroid
        for(var i = 0; i<cluster_n; i++){
            newCentroid = pinit(pointDimension);
            for(var j = 0; j<ClusterResult[i].length; j++){
                newCentroid = padd(ClusterResult[i][j], newCentroid);
            }
            ClusterCenter[i] = pdivide(newCentroid, ClusterResult[i].length);
        }
        changed=false;
        for(var i = 0; i<cluster_n; i++){
            if(!pequal(ClusterCenter[i],oldClusterCenter[i]))
                changed = true;
        }
    }//while (changed == true);
    return ClusterResult;
}

function computeDistanceBetween(a,b){
    var result = 0;
    for(var i = 0; i<a.length;i++) result += a[i] * b[i];
    return result;
}
function pinit(n){
    var result = new Array(n);
    for(var i=0;i<n;i++) result[i] = 0;
    return result;
}
function padd(a,b){
    var result = new Array(a.length);
    for(var i = 0; i<a.length;i++) result[i] = a[i] + b[i];
    return result;
}
function pdivide(a,d){
    var result = new Array(a.length);
    for(var i = 0; i<a.length;i++) result[i] = a[i] / d;
    return result;
}
function pequal(a,b){
    for(var i = 0; i<a.length;i++) 
        if(a[i] != b[i]) return false;
    return true;
}
function randomInt(max){
    return randomIntBetween(0,max);
}
function randomIntBetween(min,max){
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

如果我停止for循环(k<0)，控制台给出正确的答案。但是，如果我启动for循环(k<1)，数组ClusterCenter将始终具有一些NaN项。NaN是如何出现的?

编辑:进一步解释:如果执行了第14行for循环，上面的ClusterCenter将给出一些NaN项，为什么?

的例子

var testArray = new Array();
for(var i=0; i<100; i++) testArray.push([randomInt(-150,150),randomInt(-150,150)]);
kmeans(testArray,4);