method

cofactor

v2_2_9 - Show latest stable - 0 notes - Class: Matrix

1_8_6_287
1_8_7_72
1_8_7_330
1_9_1_378
1_9_2_180
1_9_3_125
1_9_3_392
2_1_10
2_2_9 (0)
2_4_6 (0)
2_5_5 (0)
2_6_3
What's this?

cofactor(row, column) public

Returns the (row, column) cofactor which is obtained by multiplying the first minor by (-1)**(row + column).

Matrix.diagonal(9, 5, -3, 4).cofactor(1, 1)
  => -108

Show source

# File lib/matrix.rb, line 684
  def cofactor(row, column)
    raise RuntimeError, "cofactor of empty matrix is not defined" if empty?
    Matrix.Raise ErrDimensionMismatch unless square?

    det_of_minor = first_minor(row, column).determinant
    det_of_minor * (-1) ** (row + column)
  end

cofactor

Related methods