fact: Definition matrix_mult_unf {m n p} (mat1 : Matrix R m n) (mat2 : Matrix R n p) : Matrix R m p := λ i j, Σ (λ k, (mat1 i k * mat2 k j))%rig.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.StandardFiniteSets UniMath.Combinatorics.Vectors UniMath.Algebra.RigsAndRings UniMath.Algebra.IteratedBinaryOperations UniMath.Algebra.Matrix UniMath.Algebra.Domains_and_Fields UniMath.Algebra.GaussianElimination.Auxiliary UniMath.Algebra.GaussianElimination.Vectors