method

determinant

v1_8_7_330 - Show latest stable - 0 notes - Class: Matrix

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1_8_7_72 (0)
1_8_7_330 (0)
1_9_1_378 (38)
1_9_2_180 (-23)
1_9_3_125 (0)
1_9_3_392 (0)
2_1_10 (0)
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2_5_5 (0)
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determinant() public

Returns the determinant of the matrix. If the matrix is not square, the result is 0.

Matrix[[7,6], [3,9]].determinant
  => 63

Show source

# File lib/matrix.rb, line 681
  def determinant
    return 0 unless square?
    
    size = row_size - 1
    a = to_a
    
    det = 1
    k = 0
    begin 
      if (akk = a[k][k]) == 0
        i = k
        begin
          return 0 if (i += 1) > size
        end while a[i][k] == 0
        a[i], a[k] = a[k], a[i]
        akk = a[k][k]
        det *= -1
      end
      (k + 1).upto(size) do
        |i|
        q = a[i][k] / akk
        (k + 1).upto(size) do
          |j|
          a[i][j] -= a[k][j] * q
        end
      end
      det *= akk
    end while (k += 1) <= size
    det
  end

determinant

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