_xs = null;
_ds = ds;
}
protected void set_sparse(int nzeros){
if(_len == nzeros)return;
<BUG>assert _len == _len2;
int zs = 0;</BUG>
if(_ds == null){
assert nzeros < _ls.length;
_id = MemoryManager.malloc4(_ls.length);

_xs = null;
_ds = ds;
}
protected void set_sparse(int nzeros){
if(_len == nzeros)return;
assert _len == _len2:"_len = " + _len + ", _len2 = " + _len2 + ", nzeros = " + nzeros;
int zs = 0;
if(_ds == null){
assert nzeros < _ls.length;
_id = MemoryManager.malloc4(_ls.length);
