docs: public void convertToSparse() {
          switch ( mat.getType() ) {
              case DDRM: {
                  DMatrixSparseCSC m = new DMatrixSparseCSC(mat.getNumRows(), mat.getNumCols());
                  ConvertDMatrixStruct.convert((DMatrixRMaj) mat, m,0);
                  setMatrix(m);
              } break;
              case FDRM: {
                  FMatrixSparseCSC m = new FMatrixSparseCSC(mat.getNumRows(), mat.getNumCols());
                  ConvertFMatrixStruct.convert((FMatrixRMaj) mat, m,0);
                  setMatrix(m);
              } break;
  
              case DSCC:
              case FSCC:
                  break;
              default:
                  throw new RuntimeException("Conversion not supported!");
          }
      }