public void addToArray(int offset, double[] array, int arrayOffset, int length) {
assert((offset>=0)&&(offset+length<=this.length));
double[] data=internalData();
Index index=internalIndex();
int start=index.seekPosition(offset);
int[] ixs=index.data;
int dataLength=data.length;
for (int j=start; j<dataLength; j++) {
int di=ixs[j]-offset; // index relative to offset
if (di>=length) return;