Opened 7 years ago
Closed 5 years ago
#22 closed task (wontfix)
NIP solution get a float
Reported by: | blueskythinker | Owned by: | pbelotti |
---|---|---|---|
Priority: | minor | Milestone: | |
Component: | Couenne | Version: | |
Keywords: | Cc: |
Description
hi,
I'm using couenne to solve a NIP problem, and i get a float solution.
System: Win7+ampl
couenne.exe --version couenne (Microsoft cl 15.00.21022.08 f 80x86), ASL(20100130)
AMPL model file:
param N >0,integer; param Cmax >0,integer; param Cmin >0,integer; set index:=1..N; param alreadlyDownload{index}>=0,integer; param downloadAbility{index}>=0,integer; var x{index}>=0,integer; subject to total:sum{ i in index} x[i]<=Cmax; subject to ability{i in index}: x[i]<=downloadAbility[i]; maximize gain: sum{ i in index} log(x[i]+alreadlyDownload[i]);
dataFile:
param downloadAbility:=
1 28 2 21 3 10; param N:=3; param alreadlyDownload:= 1 479 2 478 3 199; param Cmax:=10; param Cmin:=6;
and AMPL script:
reset; model model.mod; data data.dat; option solver couenne; solve; display x; display gain; display downloadAbility; display alreadlyDownload; display Cmax; display Cmin;
the output:
couenne: Optimal
x [*] := 1 2.79221e-09 2 2.84946e-09 3 10 ;
gain = 17.6836
downloadAbility [*] := 1 28 2 21 3 10 ;
alreadlyDownload [*] := 1 479 2 478 3 199 ;
Cmax = 10
Cmin = 6
thanks!
Change History (1)
comment:1 Changed 5 years ago by pbelotti
- Resolution set to wontfix
- Status changed from new to closed
Apologies for the delay in solving this, but I think this is not a real problem. Although the optimal solution is, strictly speaking, not integer, most solvers (including commercial ones) treat values like 1e-9 as integer. There is an integrality threshold in Cbc that should be used in these cases. Please refer to the Cbc documentation for this.