docs: public static void multColumns(DMatrixSparseCSC A , double []values , int offset) {
          if( values.length+offset < A.numCols )
              throw new IllegalArgumentException("Array is too small. "+values.length+" < "+A.numCols);
  
          for (int i = 0; i < A.numCols; i++) {
              int idx0 = A.col_idx[i];
              int idx1 = A.col_idx[i+1];
  
              double v = values[offset+i];
              for (int j = idx0; j < idx1; j++) {
                  A.nz_values[j] *= v;
              }
          }
      }