if (r.nextBoolean() || numRows == nonNullRows) {
m.assignRow(numRows == nonNullRows ? i : c, v);
} else {
Vector other = m.viewRow(r.nextInt(numRows));
if (other != null && other.getLengthSquared() > 0) {
m.assignRow(c, other.clone());
}
}
//n += m.getRow(c).getLengthSquared();
}
return m;