code: public T plus( double beta , T B ) {
          convertType.specify(this,B);
          T A = convertType.convert(this);
          B = convertType.convert(B);
  
          T ret = A.createLike();
          A.ops.plus(A.mat,beta,B.mat,ret.mat);
          return ret;
      }
docs: <p>
  Performs a matrix addition and scale operation.<br>
  <br>
  c = a + &beta;*b <br>
  <br>
  where c is the returned matrix, a is this matrix, and b is the passed in matrix.
  </p>
  
  @see CommonOps_DDRM#add( DMatrixD1, double , DMatrixD1, DMatrixD1)
  
  @param B m by n matrix. Not modified.
  
  @return A matrix that contains the results.