method

cofactor

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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 686
  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

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