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Matrix multiplication

  1. Sep 29, 2011 #1
    A is an M × N matrix, B is N × K and C is a K × L matrix. Consider matrix
    multiplication (AB)ij = Pk AikBkj .

    Using the formula, (AB)ij = Pk AikBkj, how would I calculate ((AB)C) and (A(BC))?
  2. jcsd
  3. Sep 29, 2011 #2


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    Just use the formula twice (on each of those products). Start with [tex]((AB)C)_{ij}=\sum_k(AB)_{ik}C_{kj}.[/tex] Now use the formula again to evaluate [itex](AB)_{ik}[/itex].
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