code: public ColumnVector multiply(ColumnVector cv)
          throws MatrixException
      {
          // Validate cv's size.
          if (nRows != cv.nRows) {
              throw new MatrixException(
                                  MatrixException.INVALID_DIMENSIONS);
          }
  
          double pv[] = new double[nRows];   // product values
  
          // Compute the values of the product.
          for (int r = 0; r < nRows; ++r) {
              double dot = 0;
              for (int c = 0; c < nCols; ++c) {
                  dot += values[r][c] * cv.values[c][0];
              }
              pv[r] = dot;
          }
  
          return new ColumnVector(pv);
      }
docs: Multiply this matrix by a column vector: this*cv
  @param cv the column vector
  @return the product column vector
  @throws numbercruncher.MatrixException for invalid size