Please replace file glpk-4.63/src/simplex/spydual.c with a new one (see attachment) and then build the package as usual.
Now your instance is solved successfully: mao@corvax:~/Desktop/glpk$ make g++ -Wall -Wextra -pedantic -O3 -g -march=native -std=c++11 -c glpk.cc -o glpk.o g++ glpk.o -lglpk -lm -o glpk mao@corvax:~/Desktop/glpk$ ./glpk GLPK Simplex Optimizer, v4.64 10 rows, 9 columns, 54 non-zeros # 0: obj = 0.000000000e+00 inf = 0.000e+00 (5) # 9: obj = 0.000000000e+00 inf = 0.000e+00 (0) OPTIMAL LP SOLUTION FOUND GLPK Simplex Optimizer, v4.64 14 rows, 9 columns, 80 non-zeros # 9: obj = 0.000000000e+00 inf = 0.000e+00 (4) # 14: obj = 0.000000000e+00 inf = 0.000e+00 (0) OPTIMAL LP SOLUTION FOUND GLPK Simplex Optimizer, v4.64 15 rows, 9 columns, 83 non-zeros # 14: obj = 0.000000000e+00 inf = 0.000e+00 (1) # 18: obj = 0.000000000e+00 inf = 0.000e+00 (0) OPTIMAL LP SOLUTION FOUND GLPK Simplex Optimizer, v4.64 17 rows, 9 columns, 93 non-zeros # 18: obj = 0.000000000e+00 inf = 0.000e+00 (2) Perturbing LP to avoid stalling [217]... Removing LP perturbation [223]... # 223: obj = 0.000000000e+00 inf = 0.000e+00 (0) 2 OPTIMAL LP SOLUTION FOUND mao@corvax:~/Desktop/glpk$ I changed the internal routine play_coef to perform more aggressive perturbation to prevent dual degeneracy even if the current dual basic solution is strongly feasible (as in your case, where the objective is zero, so all reduced costs are always zero). BTW, in your case the primal simplex would be preferable; why do you choose dual? Best regards, Andrew Makhorin
spydual.c.gz
Description: GNU Zip compressed data
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