public DoubleMatrix2D make(int rows, int columns) {
if (this == sparse) {
return new SparseDoubleMatrix2D(rows, columns);
}
if (this == rowCompressed) {
return new RCDoubleMatrix2D(rows, columns);
}
//if (this==rowCompressedModified) return new RCMDoubleMatrix2D(rows,columns);
else {
return new DenseDoubleMatrix2D(rows, columns);
}