[Help-glpk] need help on matrix multiplication

[Alessandro Urbano]

I had some trouble on creating a matrix multiplication.

This is what I wrote


s.t. Costraint1{l in A,d in B} : sum{j in C}   D[l,j] * E[j,d]  <= 13;

I try to find some documentation on internet and I've found that is not that the correct way to implement matrix multiplication.I've found this:

>>>
 how can I mutiply a m*n matrix (A) by a n*1 matrix(B)?

Given, say,

   param A {1..m, 1..n};
   param B {1..n};

you can write:

   sum {j in 1..n} A[i,j] * B[j]
to get the ith element of A times B.  There is no "matrix multiplication"
operator in AMPL that would let you write simply "A * B", however.
>>>

I know that gmpl is a subset of AMPL ,then if I don't find an instruction to do this operation in AMPL,surely I don't find that instruction in gmpl (i think so,even some difference that I don't know)

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