Method: Mittsu::Matrix4#determinant

Defined in:

lib/mittsu/math/matrix4.rb

#determinant ⇒ Object

# File 'lib/mittsu/math/matrix4.rb', line 295

def determinant
  te = self.elements
  n11 = te[0]; n12 = te[4]; n13 = te[8]; n14 = te[12]
  n21 = te[1]; n22 = te[5]; n23 = te[9]; n24 = te[13]
  n31 = te[2]; n32 = te[6]; n33 = te[10]; n34 = te[14]
  n41 = te[3]; n42 = te[7]; n43 = te[11]; n44 = te[15]
  #TODO: make this more efficient
  #(based on http:#www.euclideanspace.com/maths/algebra/matrix/functions/inverse/fourD/index.htm)
  n41 * (n14 * n23 * n32 - n13 * n24 * n32 - n14 * n22 * n33 + n12 * n24 * n33 + n13 * n22 * n34 - n12 * n23 * n34) +
  n42 * (n11 * n23 * n34 - n11 * n24 * n33 + n14 * n21 * n33 - n13 * n21 * n34 + n13 * n24 * n31 - n14 * n23 * n31) +
  n43 * (n11 * n24 * n32 - n11 * n22 * n34 - n14 * n21 * n32 + n12 * n21 * n34 + n14 * n22 * n31 - n12 * n24 * n31) +
  n44 * (-n13 * n22 * n31 - n11 * n23 * n32 + n11 * n22 * n33 + n13 * n21 * n32 - n12 * n21 * n33 + n12 * n23 * n31)
end