 feat(linear_algebra/matrix): multiplying `is_basis.to_matrix` and `linear_map.to_matrix` (#4650)
 feat(linear_algebra/matrix): multiplying `is_basis.to_matrix` and `linear_map.to_matrix` (#4650)

This basically tells us that `is_basis.to_matrix` is indeed a basis change matrix.





leanprover-community/mathlib,leanprover-community/mathlib