W***Y
发帖数: 27 | 1 Let A be an m*n matrix and B be an n*p matrix. Prove that AB can be written
as a sum of n matries of rank at most one
谢谢！ | l*****e
发帖数: 65 | 2 You can write the nxp matrix as the sum of n matrices, each is n by p size,
consisting of one row of B and zeros elsewhere .
Since each such matrix is of rank at most 1, the product with A is of rank
at most 1 too.
QED |
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