code: public static void checkIdenticalShape(DMatrixRBlock A , DMatrixRBlock B ) {
          if( A.blockLength != B.blockLength )
              throw new IllegalArgumentException("Block size is different");
          if( A.numRows != B.numRows )
              throw new IllegalArgumentException("Number of rows is different");
          if( A.numCols != B.numCols )
              throw new IllegalArgumentException("NUmber of columns is different");
      }
docs: <p>
  Checks to see if the two matrices have an identical shape an block size.
  </p>
  
  @param A Matrix.
  @param B Matrix.