> Hi guys, I am new in GLPK use and I would like to ask you about some > solution that I get: Basically I define an LP problem where the > variable x10, x11 and x12 take values bw. 0 and 1 and the sum of > x10+x11+x12 = 1, according to that and for 18 structural variables I > get the following answer:
> ./a.out > 0: obj = 0.000000000e+00 infeas = 6.000e+00 (0) > * 8: obj = 1.300000000e+03 infeas = 0.000e+00 (0) > * 13: obj = 1.600000000e+03 infeas = 8.171e-16 (0) > OPTIMAL SOLUTION FOUND > z = 1600 > x10 = 0; x11 = 0; x12 = 1 > x20 = 0; x21 = 0; x22 = 1 > x30 = 0; x31 = 0; x32 = 1 > x40 = 0; x41 = 0; x42 = 1 > x50 = 1; x51 = 0; x52 = -8.17124e-16 > x60 = 1; x61 = 0; x62 = 0 > The value of z correspond to the right value, but how do I understand > the value of x52??, is it a real "0" value and how is it related to > the "infeas = 8.171e-16" value?, does it mean that my answer is wrong > (since I should have only expect x50 = 1; x51 = 0; x52 = 0)? The solution is correct. You should understand x52 = -8.17124e-16 as zero within a working precision. To perform calculations the glpk simplex solver uses floating-point arithmetic, so it reports a solution, which is an approximation to the mathematically exact result. _______________________________________________ Help-glpk mailing list Help-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/help-glpk