Hello Andrew, on a i386 Ubuntu with glpk-4.33 ./glpsol -m test1.mod --check --wcpxlp test.clp resulted in:
\* Problem: test1 *\ Minimize z: + X(1,b2) + 2 X(1,b3) + X(1,b5) Subject To Bounds X(1,b2) free X(1,b3) free X(1,b5) free End Best regards Xypron Peter Ingerfeld-2 wrote: > > 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 mailing list > Help-glpk@gnu.org > http://lists.gnu.org/mailman/listinfo/help-glpk > > -- View this message in context: http://www.nabble.com/Sets-of-ordered-pairs%3A-Differences-between-AMPL-and-GNU-MathProg-tp20561226p20566689.html Sent from the Gnu - GLPK - Help mailing list archive at Nabble.com. _______________________________________________ Help-glpk mailing list Help-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/help-glpk