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A simple question

is a (5x2)*(2x5) = a (5x5) matrix?

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    Yes. ${}{}{}{}{}$2011-05-02
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    http://en.wikipedia.org/wiki/Matrix_multiplication#Technical_Details2011-05-02
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    Yes, the matrix product $AB$ is defined when $A$ has dimensions $n\times m$ and $B$ has dimensions $m\times k$ for any integers $n,m,k$, and the resulting matrix will have dimensions $n\times k$.2011-05-02
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    How about a (3X2) * (5X3) is this a 3x5?... this is my last question to finally understand this2011-05-02
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    @edprof: that product is not defined in that order (the dimensions $2$ and $5$ on the inside don't match). In the other order, it's $5 \times 2$.2011-05-02
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    @edprof: As Qiachu and matt have said, the right-most dimension of the matrix on the left must match the left-most dimension of the matrix on the right, or else the product is meaningless. The dimension on the left represents the number of rows in a matrix; the dimension on the right represents the number of columns of the matrix. Check out the link provided by DJC for more details.2011-05-02
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    @All: why did 'community' bring this back to the front page?2011-06-04
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    @mixedmath, my understanding is that "Community" somehow selects questions where no answer has been accepted and resurrects them in the hope that the questioner will find some answer, old or new, acceptable.2011-06-04

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