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Math Help - special matrix product

  1. #1
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    special matrix product

    Hi, I'm not native English, what is the name the following product. Let a n-column vector and b m-row vector, than c = a b resultes a n-by-m-matrix:
    c_ij = a_i * b_j.
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  2. #2
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    Quote Originally Posted by Skalkaz View Post
    Hi, I'm not native English, what is the name the following product. Let a n-column vector and b m-row vector, than c = a b resultes a n-by-m-matrix:
    c_ij = a_i * b_j.
    i don't know if there's a name for this but what you've defined is simply this \bold{c}=(\bold{ba})^T.
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  3. #3
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    What does ba mean?
    b and a are vector, and n <>= m.

    This product is very usefull sometimes,for example:
    the matrix of the tranformation r --> a(br) is
    T = a b
    where a, b, r is spatial vector, and br is scalar product
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  4. #4
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    \bold{b} is an m \times 1 vector and \bold{a} an 1 \times n. so \bold{b}\bold{a} is an m \times n matrix. clearly (\bold{b}\bold{a})^T would be the matrix that you called \bold{c}.
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  5. #5
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    Oh, you are absolutly right.
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