How do you calculate the determinant of an NxN matrix C# ?
The OP posted another question asking specifically about 4x4 matrices, which has been closed as an exact duplicate of this question. Well, if you're not looking for a general solution but instead are constrained to 4x4 matrices alone, then you can use this ugly looking but tried-and-true code:
public double GetDeterminant() {
var m = _values;
return
m[12] * m[9] * m[6] * m[3] - m[8] * m[13] * m[6] * m[3] -
m[12] * m[5] * m[10] * m[3] + m[4] * m[13] * m[10] * m[3] +
m[8] * m[5] * m[14] * m[3] - m[4] * m[9] * m[14] * m[3] -
m[12] * m[9] * m[2] * m[7] + m[8] * m[13] * m[2] * m[7] +
m[12] * m[1] * m[10] * m[7] - m[0] * m[13] * m[10] * m[7] -
m[8] * m[1] * m[14] * m[7] + m[0] * m[9] * m[14] * m[7] +
m[12] * m[5] * m[2] * m[11] - m[4] * m[13] * m[2] * m[11] -
m[12] * m[1] * m[6] * m[11] + m[0] * m[13] * m[6] * m[11] +
m[4] * m[1] * m[14] * m[11] - m[0] * m[5] * m[14] * m[11] -
m[8] * m[5] * m[2] * m[15] + m[4] * m[9] * m[2] * m[15] +
m[8] * m[1] * m[6] * m[15] - m[0] * m[9] * m[6] * m[15] -
m[4] * m[1] * m[10] * m[15] + m[0] * m[5] * m[10] * m[15];
}
It assumes you store your vector data in a 16-element array called _values
(of double
in this case, but float
would work too), in the following order:
0, 1, 2, 3,
4, 5, 6, 7,
8, 9, 10, 11,
12, 13, 14, 15