calculating matrix determinants with laplace expansion

[paula-coder-646]

Hi, I would love to contribute a better than O(n^3) so naive implementation of matrix determinants using the laplace expansion. Please assign it to me as it would be my first chance to contribute to hacktoberfest and I recently learned about it in my algebra module :D

[paula-coder-646]

nvm Its already part of the matrix class :D