https://en.wikipedia.org/wiki/Crout_matrix_decomposition https://www.gamedev.net/tutorials/programming/math-and-physics/matrix-inversion-using-lu-decomposition-r3637/
https://en.wikipedia.org/wiki/Crout_matrix_decomposition
https://www.gamedev.net/tutorials/programming/math-and-physics/matrix-inversion-using-lu-decomposition-r3637/