proposition: Lemma sum_id_pointwise_prod { n : nat } (v : Vector R n) (i : ⟦ n ⟧%stn) : Σ ((identity_matrix i) *pw v) = (v i).
proof: Proof. apply sum_stdb_vector_pointwise_prod. Defined.
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