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Tensor Product of Two Matrices coming from Algebra Representations

asked 13 years ago

ChrisBerg gravatar image

updated 12 years ago

vdelecroix gravatar image

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?

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What you need is perhaps "tensor sum", "Kronecker sum".

gundamlh gravatar imagegundamlh ( 11 years ago )

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answered 12 years ago

vdelecroix gravatar image

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

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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 gravatar imagegundamlh ( 11 years ago )

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 gravatar imagegundamlh ( 11 years ago )

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Asked: 13 years ago

Seen: 5,807 times

Last updated: Aug 03 '12