docs: public static boolean isEquals(DMatrix a, DMatrix b ) {
          if( a.getNumRows() != b.getNumRows() || a.getNumCols() != b.getNumCols() )
              return false;
  
          final int numRows = a.getNumRows();
          final int numCols = a.getNumCols();
  
          for (int row = 0; row < numRows; row++) {
              for (int col = 0; col < numCols; col++) {
                  if( !(a.unsafe_get(row,col) == b.unsafe_get(row,col)))
                      return false;
              }
          }
          return true;
      }