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[Help-glpk] Some questions...
From: |
Falk Hueffner |
Subject: |
[Help-glpk] Some questions... |
Date: |
10 Oct 2001 00:08:54 +0200 |
User-agent: |
Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.5 (anise) |
Hi,
a while ago I asked about using glpk to solve integer inequations, and
it actually works :) Now I have a few questions... I wrote a script
to generate the problem corresponding to some input. Its output looks
like this:
#define AAA 1
#define AAB 2
#define ABA 1
#define ABC 1
#define MAXD 5
model CS;
integer variables
DUMMY, AAA_A, AAB_A, AAB_B, ABA_A, ABA_B, ABC_A, ABC_B, ABC_C;
constraints
D0, D1, D2,
E0, E1, E2, E3, E4, E5, E6, E7,
S0, S1, S2, S3,
Z;
D0 := + AAB_B + ABA_B + ABC_B + ABC_C <= MAXD;
D1 := + AAB_B + ABA_A + ABC_A + ABC_C <= MAXD;
D2 := + AAB_A + ABA_B + ABC_A + ABC_B <= MAXD;
E0 := AAA_A >= 0;
E1 := AAB_A >= 0;
E2 := AAB_B >= 0;
E3 := ABA_A >= 0;
E4 := ABA_B >= 0;
E5 := ABC_A >= 0;
E6 := ABC_B >= 0;
E7 := ABC_C >= 0;
S0 := + AAA_A = AAA;
S1 := + AAB_A + AAB_B = AAB;
S2 := + ABA_A + ABA_B = ABA;
S3 := + ABC_A + ABC_B + ABC_C = ABC;
Z := DUMMY = 0;
minimize Z;
end;
Some questions:
* I use cpp to define some constants. Can I do this with glpk
language constructs?
* The generated variable names can get very long and hit a limit (32
or so). Would it be easy to remove this limit?
* I introduce a lot of variables (E_x) just to state all variables
have to be positive. Is there a better way?
* Also, is there a better way than this "DUMMY" to express I don't
really want to optimize anything?
Falk
PS: Thanks a lot for this great software. With it, we can solve much
larger problems than with our prior approaches.
PPS: If there is any interest, I could try to make a Debian package of
glpk.
- [Help-glpk] Some questions...,
Falk Hueffner <=