[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Help-glpk] Sets of ordered pairs: Differences between AMPL and GNU Math
From: |
Peter Ingerfeld |
Subject: |
[Help-glpk] Sets of ordered pairs: Differences between AMPL and GNU MathProg |
Date: |
Tue, 18 Nov 2008 18:01:29 +0300 |
There is an inhomogeneity between AMPL and MathProg in the way sets of
ordered pairs are being iterated over by two (or more) sum{} statements
which are linked by an iterator variable.
Consider the following sample:
---------------------------
set A :={1..5};
set B :={"b1", "b2", "b3", "b4", "b5"};
set D within {A,B} := {(1,"b2"), (1,"b3"), (1,"b5"), (3,"b3")};
var X {D};
minimize z:
sum{a in (1..5)} sum {(a,b) in D} X[1,b];
---------------------------
AMPL generates:
MIN X[1,b2] + 2 X[1,b3] + X[1,b5]
MathProg generates:
MIN 5 X[1,b2] + 5 X[1,b3] + 5 X[1,b5]
Obviously AMPL links the inner and outer sum{} statements by variable 'a'
and MathProg doesn't.
Bug or feature?
Dr. Peter Ingerfeld
MOPS Optimierungssysteme GmbH & Co KG
- [Help-glpk] Sets of ordered pairs: Differences between AMPL and GNU MathProg,
Peter Ingerfeld <=
Re: [Help-glpk] Sets of ordered pairs: Differences between AMPL and GNU MathProg, xypron, 2008/11/18