# Tensor Product of Two Matrices coming from Algebra Representations

 0 Is there a command in sage to compute the tensor product of two Matrices coming from Algebra representations? In groups, x(v tensor w) = xv tensor xw, and the sage command Matrix1.tensor_product(Matrix2) appears to give the matrix corresponding to this. But in an algebra x(v tensor w) = xv tensor w + v tensor xw. How can I compute the corresponding matrix here? asked May 03 '11 ChrisBerg 1 ● 1 ● 1 vdelecroix 1422 ● 6 ● 22 ● 39 What you need is perhaps "tensor sum", "Kronecker sum".gundamlh (Nov 13)

 1 Hi, If M1 is your first matrix (of dimension n1) and M2 is your second matrix (of dimension n2), then the answer should be: M1.tensor_product(identity_matrix(n2)) + identity_matrix(n1).tensor_product(M2)  Vincent posted Aug 03 '12 vdelecroix 1422 ● 6 ● 22 ● 39 M1 "tensor_sum" M2 = eye(n2) "tensor_product" M1 + eye(n1) "tensor_product" M2 .. the tensor product operation is not commutative, I guess. Hence, identity_matrix(n2).tensor_product(M1) + M2.tensor_product(identity_matrix(n1)) , or?gundamlh (Nov 13)but this command is too long.. we have to write a my_function or the function "tensor_sum" is already implemented in some packages, such as maxima, Scipy ....gundamlh (Nov 13)

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