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## [Help-glpk] "multiplication of linear forms not allowed"

**From**: |
Reginald Beardsley |

**Subject**: |
[Help-glpk] "multiplication of linear forms not allowed" |

**Date**: |
Sun, 21 Oct 2012 07:45:52 -0700 (PDT) |

I'm trying to apply the following constraint following a suggestion by xypron:
var M{J} ,binary;
var B{J,K} ,>= 0;
s.t. a{j}: -M[j]*sum{k in K}B[j,k] <= A[j] <= M[j]*sum{k in K}B[j,k];
The goal being to force A[j] = 0 if the sum over k of B[j,k] = 0;
glpsol 4.47 exits w/ the message in the subject line. I found Steglich's post
of last month, but am having trouble w/ translating the notation in the CMPL
1.7.0 manual to GMPL.
>*From context, I'm guessing that overbar indicates the maximum and underbar the *
>*minimum, but I can find nothing to confirm that. The first equation in section *
>*8.3.1 appears to have a typo as there is no underbar in the range *
>*specification. Even if I assume the typo, and explicitly specify the *
>*additional variables and constraints, I still get the subject line message. *
>*Just at a different point.*
Is it possible to do this in GMPL? If so, how?
At the moment, the only option I can see would be to make an initial solution
w/o the constraint and then recast the problem and solve again.
Thanks,
Reg

**[Help-glpk] "multiplication of linear forms not allowed"**,
*Reginald Beardsley* **<=**