public int[] nonZeroPositionsInRow(int i, int fromColumn, int toColumn) {
int[] positions = new int[nonZerosInRow(i, fromColumn, toColumn)];
int n = 0;
ByteVectorIterator it = nonZeroRowIterator(i, fromColumn, toColumn);
while (it.hasNext()) {
it.next();
positions[n++] = it.index();
}
return positions;
}