Re: [Help-glpk] Sets of ordered pairs: Differences between AMPL and GNU MathProg

[xypron]

Hello Andrew,

64bit Windows Server 2003 with the 64bit glpsol executable available as 
http://downloads.sourceforge.net/winglpk/glpsol-4.33_64bit.zip?modtime=1225755338&big_mirror=0
glpsol-4.33_64bit.zip  at
http://winglpk.sourceforge.net http://winglpk.sourceforge.net 
also gives:
Minimize
 z: + X(1,b2) + 2 X(1,b3) + X(1,b5)

Best regards

Xypron


xypron wrote:
> 
> 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
>> address@hidden
>> http://lists.gnu.org/mailman/listinfo/help-glpk
>> 
>> 
> 
> 

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