code: public static RealMatrix getColumRange (RealMatrix matrix, int start, int end) {
          return matrix.getSubMatrix(0, matrix.getRowDimension() - 1, start, end);
      }
docs: Returns the column range from the matrix as a new matrix.
  
  @param matrix The input matrix
  @param start The index of the column to start with (inclusive)
  @param end The index of the column to end with (inclusive)
  @return A new matrix with columns specified