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From: | Meketon, Marc |
Subject: | RE: [Fwd: Discussion on GLPK] |
Date: | Tue, 19 Apr 2022 13:37:32 +0000 |
Hello Mingyue, Typically when I see that many coefficients, it suggests that you need to reformulate your problem. One example. Suppose that X1, X2, X3, …, X20 are non-negative integers, and you have equations like X1 <= b1, X1 + X2 <= b2, X1 + X2 + X3 <= b3, …, X1 + X2 + X3 + … + X20
<= b20. That has 20*(20+1)/2 = 210 coefficients A reformulation would be to introduce variables Y1, Y2, Y3, …, Y20, then you could write Y1 = X1, Y2 = Y1 + X2, Y3 = Y2 + X3, … , Y20 = Y19 + X20, and have the Y’s have upper
bounds: Y1 <= b1, Y2 <= b2. That’s 59 coefficients. -Marc From: Help-glpk <help-glpk-bounces+marc.meketon=oliverwyman.com@gnu.org>
On Behalf Of Andrew Makhorin -------- Forwarded Message -------- Date: Tue, 19 Apr 2022 10:00:54 +0800 Subject: Discussion on GLPK From: jimingyue <20s103192@stu.hit.edu.cn> Dear developer, Hope you are well! Recently, I use GLPK to solve a LP problem in my graduation project. My coefficient matrix is very large so that there is a bug
“glp_load_matrix: ne=1889848940; too many constraint coefficients”. I google this hint and find GLPK requires the size of coefficient matrix is less than 500000000. So I have two questions as follows,
1.
Why the size is required less than 500000000?
2.
If I cannot limit the size within 500000000, is there some way to solve my LP problem using GLPK? If the answer is yes, do I need to modify any code? ? If the answer is no, could you give
me some advices to solve my problem? Looking forward to your reply! Really appreciate your help! Best regards, Mingyue Ji This e-mail and any attachments may be confidential or legally privileged. If you received this message in error or are not the intended recipient, you should destroy the e-mail message and any attachments or copies, and you are prohibited from retaining, distributing, disclosing or using any information contained herein. Please inform us of the erroneous delivery by return e-mail. Thank you for your cooperation. For more information on how we use your personal data please see our Privacy Notice. |
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