Re: [Help-glpk] Inputting a large sparse matrix in GLPK data file

[Andrew Makhorin]

> I am a newbie to GLPK - but am enjoying this !

> I need to input (or specify)  a large sparse integer matrix A which is
> say 1500 X 1500.
> Only a few entries are integers, say 100 of them are integers and the
> rest are zeros.
> How does one go about inputting this in to GLPK ?

> How is this done neatly in GLPK ? (ie initializing all entries of A to
> zero) and inputting only the non-zero ones
> I was trying something along the lines of  saying (in the MOD file)

> set I :=  1..1500;
> set J := 1..1500;
> param A{i in I, j in J}, >=0, default 0.0;

> How are the non-zero entries specified then ?
> When I tried setting [in the DAT file]

> A[1,2] := 5; A[3, 2]:=9, A[1,6]: = 6;
> I get an error.

> Please help !!!

param A := [1,2] 5 [3,2] 9 [1,6] 6;

Note that there are other, more convenient ways to specify parameters
in the data section; see example models included in the distribution.