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## [Help-glpk] Re: Matrix definition

**From**: |
Andrew Makhorin |

**Subject**: |
[Help-glpk] Re: Matrix definition |

**Date**: |
Thu, 02 Dec 2010 10:09:35 +0300 |

>* > I have a large linear programming problem to solve where the constraint *
>* matrix A in Ax<=b is sparse.*
>* > I defined:*
>* > *
>* > param A{i in 1..n, j in 1..m} default 0.0;*
>* > *
>* > So now in the data I would like to just define the non-zero values.*
>* > *
>* > How can I do that? How do I address each element?*
>* > *
>* > I tried *
>* > *
>* > data;*
>* > param A[2,3]:=5;*
>* > param A[6,1]:=2;*
>* > *
>* > Etc.*
>* > *
>* > But it does not work.*
>* > *
>* > Any ideas?*
data;
param A := [2,3] 5 [6,1] 2;
There exist several formats to specify data for 2d arrays. For more
details please see the mathprog language reference (doc/gmpl.pdf) and
examples included in the glpk distribution (egypt.mod, train.mod, etc.).

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**[Help-glpk] Re: Matrix definition**,
*Andrew Makhorin* **<=**