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## Re: [Help-glpk] how to restrict variables under 1e-3

 From: Antti Lehtila Subject: Re: [Help-glpk] how to restrict variables under 1e-3 Date: Thu, 25 Oct 2018 17:38:19 +0300 User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1

 Hi, I tested with using variable bounds, and it worked well even with 1e-5 / 2e-5 : #------------------------- param delta_min default 1e-5; param delta_max default 2e-5; var x >= delta_min, <= delta_max; minimize f: x; solve; #------------------------- Regards, AL On 23.10.2018 19:16, Thiago Neves wrote: Hi, all! I need to solve a problem in witch some statements may restricts a variable above a small value, e.g. 1e-4. But after solving, GLPSOL is setting this variable equals to zero. If I run this problem using "--exact" argument, it works as expected, but it uses much more memory. Is there any argument or work arround to o run this problem in glpsol without using exact arithimetic? Example: In the simple example attached, the minimun value for "x" must be "delta_min", but in my tests: if delta_min < 1e-3, x results in 0 (even for delta_min = 9.999e-4) (1) - Using "statement_test_0.0001.dat" file, the result is wrong: 3 rows, 1 column, 3 non-zeros Preprocessing... ~     0: obj =  0.000000000e+000  infeas = 0.000e+000 OPTIMAL SOLUTION FOUND BY LP PREPROCESSOR Time used:   0.0 secs Memory used: 0.1 Mb (88615 bytes) Display statement at line 14 x.val = 0 x = 0.0000000000000000 Display statement at line 17 delta_min = 0.0001 Display statement at line 18 delta_max = 0.0002 Model has been successfully processed (2) - Using "statement_test_0.001.dat" file, the result is correct: 3 rows, 1 column, 3 non-zeros Preprocessing... ~     0: obj =  1.000000000e-003  infeas = 0.000e+000 OPTIMAL SOLUTION FOUND BY LP PREPROCESSOR Time used:   0.0 secs Memory used: 0.1 Mb (88615 bytes) Display statement at line 14 x.val = 0.001 x = 0.0010000000000000 Display statement at line 17 delta_min = 0.001 Display statement at line 18 delta_max = 0.002 Model has been successfully processed (3) - Running (1) with "--exact" argument, the result is correct, but uses more memory: glp_exact: 3 rows, 1 columns, 3 non-zeros GLPK bignum module is being used (Consider installing GNU MP to attain a much better performance.)       0:   infsum =                 0.0001   (0)       1:   infsum =                      0   (0) *     1:   objval =                 0.0001   (0) *     1:   objval =                 0.0001   (0) OPTIMAL SOLUTION FOUND Time used:   0.0 secs Memory used: 0.1 Mb (92819 bytes) Display statement at line 14 x.val = 0.0001 x = 0.0001000000000000 Display statement at line 17 delta_min = 0.0001 Display statement at line 18 delta_max = 0.0002 Model has been successfully processed Thanks for your help! Att, Thiago Henrique Neves -- Thiago H. Neves (31) 98608-0666 ```_______________________________________________ Help-glpk mailing list address@hidden https://lists.gnu.org/mailman/listinfo/help-glpk ```

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