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> ยท M is a large constant, says, 1e16 The problem is that the M is very large, which results in reduced accuracy in the calculations. Ideally, one would use the smallest M that will do what you want, even different values of M for different constraints. In this example, M = 1 will do, but other small values are acceptable, up to 49. > It only happens once x is in a small range, such as [0, 0.0005]. GLPK has code to reduce such big M values, but for the constraint "x - M a < 0", M can be as low as the upper bound of x, which is below the threshold (0.001) used to avoid other accuracy issues, so only the M in "y - M b < 0" is reduced to 1 (upper bound of y) as seen in the following line; > 1 constraint coefficient(s) were reduced If the upper bound of x is 0.001 or more, both M values are reduced and the problem can be solved correctly. > I also notice that some constraint have been remove from output from > solver: The constraints removed are "x + M a > 0" and "y + M b > 0" that are always true. Best Regards, Chris Matrakidis _______________________________________________ Bug-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/bug-glpk
