-------- Forwarded Message -------- From: Meketon, Marc <[email protected]> To: [email protected] <[email protected]> Subject: possible bug in 4.52 Date: Thu, 25 Jul 2013 12:31:54 -0500
Andrew,
Last night I began to create an integer program for finding which days
to perform periodic maintenance. The idea is to organize periodic
maintenance to reduce the number of times the item goes into maintenance
while not increasing the number of hours of total maintenance too much.
I am using the latest version of GUSEK with the 32-bit version 4.52 GLPK
build.
When solving the attached model, if
param MTCE_EVENTS_COST := 0.0;
then I get a solution. Not the solution that I want, but at least it
gets a solution.
If that is changed to
param MTCE_EVENTS_COST := 0.01;
then the model does not solve. Sometimes, I receive the message
Assertion failed: piv1 != 0.0
Error detected in file ..\src\glpspx02.c at line 3026
>Exit code: 3 Time: 444.488
Since the assertion failed, it may be due to a bug in GLPK.
More often, for the same problem, I receive
Error: unable to factorize the basis matrix (1)
Sorry, basis recovery procedure not implemented yet
ios_driver: unable to solve current LP relaxation; glp_simplex returned
5
+1664019: mip = not found yet >= 2.855670500e+003 (11689;
536)
glp_intopt: cannot solve current LP relaxation
Time used: 270.0 secs
Memory used: 25.4 Mb (26609330 bytes)
>Exit code: 0 Time: 270.581
As a final note, I really wanted to add the constraint below, but when I
do the code reaches various instabilities and does not solve.
subject to total_bins: sum{d in DAYS} x[d] <= 215;
[The “215” is a parameter that will vary]
-Marc
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>C:\gusek\glpsol.exe --cover --clique --gomory --mir -m "IP_model.mod"
GLPSOL: GLPK LP/MIP Solver, v4.52
Parameter(s) specified in the command line:
--cover --clique --gomory --mir -m IP_model.mod
Reading model section from IP_model.mod...
138 lines were read
Reading MTCE_NEEDS...
Connected to ACCESS 04.00.0000 - D:\AirlineMaintenanceOptimization\AirlineMtce
SELECT NG_Aircraft, left([Description],100) as [desc], Initial_Days,
Repeat_Days, Hours FROM MTCE_NEEDS WHERE Repeat_Days Is Not Null And
Repeat_Days > 0 AND Hours Is Not Null
param : REPEAT_DAYS : total_hours :=
180 10.271000
8 26.507500
3650 612.473000
2190 541.311500
4382 68.544000
910 67.548000
2920 595.771000
4380 87.108000
600 6.140000
1800 5.850000
730 135.613000
90 15.529500
365 7.956000
1825 30.937500
15 0.735000
1200 18.465000
1095 41.280000
150 0.230000
30 5.290000
540 0.390000
1000 5.190000
240 6.900000
485 2.760000
545 11.470500
4 0.483000
500 2.359000
8760 1.725000
1500 9.750000
1460 28.175000
5475 10.350000
60 0.115000
3000 69.960000
250 0.650000
Generating Four_Eight_Day_Fixed...
Generating DaysMtcePerformed...
Generating MtceRepeatDays...
Generating MtceIncreasing...
Generating AssignedRepetitionToOneDay...
Generating mtce_hours...
Model has been successfully generated
GLPK Integer Optimizer, v4.52
1890 rows, 2988 columns, 15506 non-zeros
2988 integer variables, all of which are binary
Preprocessing...
128 hidden packing inequaliti(es) were detected
8 hidden covering inequaliti(es) were detected
308 constraint coefficient(s) were reduced
746 rows, 2400 columns, 11114 non-zeros
2400 integer variables, all of which are binary
Scaling...
A: min|aij| = 1.000e+000 max|aij| = 7.500e+002 ratio = 7.500e+002
GM: min|aij| = 8.629e-001 max|aij| = 1.159e+000 ratio = 1.343e+000
EQ: min|aij| = 7.580e-001 max|aij| = 1.000e+000 ratio = 1.319e+000
2N: min|aij| = 4.219e-001 max|aij| = 1.500e+000 ratio = 3.556e+000
Constructing initial basis...
Size of triangular part is 746
Solving LP relaxation...
GLPK Simplex Optimizer, v4.52
746 rows, 2400 columns, 11114 non-zeros
0: obj = 2.855630500e+003 infeas = 1.709e-001 (0)
* 112: obj = 2.856081402e+003 infeas = 0.000e+000 (0)
* 128: obj = 2.855636333e+003 infeas = 0.000e+000 (0)
OPTIMAL LP SOLUTION FOUND
Integer optimization begins...
Gomory's cuts enabled
MIR cuts enabled
Cover cuts enabled
Clique cuts enabled
Constructing conflict graph...
Conflict graph has 1970 + 432 = 2402 vertices
+ 128: mip = not found yet >= -inf (1; 0)
Cuts on level 0: cov = 5; clq = 1;
+ 28147: mip = not found yet >= 2.855658000e+003 (203; 11)
+ 58785: mip = not found yet >= 2.855660500e+003 (382; 27)
+ 94393: mip = not found yet >= 2.855660500e+003 (538; 38)
+126326: mip = not found yet >= 2.855660500e+003 (715; 54)
+156814: mip = not found yet >= 2.855660500e+003 (885; 63)
+186113: mip = not found yet >= 2.855660500e+003 (1147; 70)
+207718: mip = not found yet >= 2.855660500e+003 (1447; 88)
+230362: mip = not found yet >= 2.855660500e+003 (1722; 101)
+252534: mip = not found yet >= 2.855660500e+003 (1967; 115)
+273999: mip = not found yet >= 2.855660500e+003 (2307; 123)
+291265: mip = not found yet >= 2.855660500e+003 (2625; 140)
Time used: 60.0 secs. Memory used: 9.5 Mb.
+325965: mip = not found yet >= 2.855660500e+003 (2876; 151)
+355878: mip = not found yet >= 2.855660500e+003 (3097; 169)
+385102: mip = not found yet >= 2.855660500e+003 (3343; 182)
+420010: mip = not found yet >= 2.855660500e+003 (3574; 188)
+449667: mip = not found yet >= 2.855660500e+003 (3764; 197)
+481443: mip = not found yet >= 2.855660500e+003 (3943; 205)
+508115: mip = not found yet >= 2.855660500e+003 (4152; 217)
+540768: mip = not found yet >= 2.855660500e+003 (4333; 227)
+572770: mip = not found yet >= 2.855660500e+003 (4527; 235)
+600177: mip = not found yet >= 2.855660500e+003 (4733; 247)
+628010: mip = not found yet >= 2.855660500e+003 (4930; 256)
+657785: mip = not found yet >= 2.855660500e+003 (5149; 270)
Time used: 120.0 secs. Memory used: 13.9 Mb.
+692959: mip = not found yet >= 2.855660500e+003 (5388; 276)
+721941: mip = not found yet >= 2.855660500e+003 (5601; 282)
+747093: mip = not found yet >= 2.855660500e+003 (5847; 298)
+773096: mip = not found yet >= 2.855660500e+003 (6117; 315)
+796022: mip = not found yet >= 2.855660500e+003 (6396; 330)
Assertion failed: piv1 != 0.0
Error detected in file ..\src\glpspx02.c at line 3026
>Exit code: 3 Time: 444.488
model.mod
Description: model.mod
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