Right way to warm/hot start CLP

[fontanf]

Hi,

I have a first mode which I solve with CLP.
I would like to solve variants of the problem for which only the bounds change. These new problems are in different Clp_Simplex structures which have the same size and the same variable ordering as the initial Clp_Simplex structure. What is the right way to extract the warm/hot start information from the initial Clp_Simplex and pass it to the new Clp_Simplex structures?
I see a CoinWarmStartBasis * getBasis () const method in the documentation https://www.coin-or.org/Doxygen/Clp/classClpSimplex.html but no setBasis method.

I would also like to solve variants with different objectives or additional constraints. Is there something useful that can be done to warm/hot start Clp in this case?

[jjhforrest]

ClpSimplex.?pp - writeBasis and readBasis.

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On 09/09/2021 16:54, Florian Fontan wrote: Hi, I have a first mode which I solve with CLP. I would like to solve variants of the problem for which only the bounds change. These new problems are in different |Clp_Simplex| structures which have the same size and the same variable ordering as the initial |Clp_Simplex| structure. What is the right way to extract the warm/hot start information from the initial |Clp_Simplex| and pass it to the new |Clp_Simplex| structures? I see a |CoinWarmStartBasis * getBasis () const| method in the documentation https://www.coin-or.org/Doxygen/Clp/classClpSimplex.html <https://www.coin-or.org/Doxygen/Clp/classClpSimplex.html> but no |setBasis| method. I would also like to solve variants with different objectives or additional constraints. Is there something useful that can be done to warm/hot start Clp in this case? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#205>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABWJYHAUR2CXS3FGLHFYXCDUBDKERANCNFSM5DXOQO5Q>. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[fontanf]

These methods will cause disk accesses. I would have expected some C/C++ structures to store rather than files to write. Is the best solution to copy the ClpSimplex object with the copy constructor and then to modify it? In this case, I can't find the copy constructor in the C interface https://www.coin-or.org/Doxygen/Clp/Clp__C__Interface_8h.html

[jjhforrest]

With C++ If just bounds changing (any way - no change in number rows/columns) - ClpSimplex alreadySolved and ClpSimplex modified modified.moveInfo(&alreadySolved); // If just bounds then could be ,true) just to do basis status Will work with different objectives. Not experienced using C interface.

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On 10/09/2021 13:20, Florian Fontan wrote: These methods will cause disk accesses. I would have expected some C/C++ structures to store rather than files to write. Is the best solution to copy the |ClpSimplex| object with the copy constructor and then to modify it? In this case, I can't find the copy constructor in the C interface https://www.coin-or.org/Doxygen/Clp/Clp__C__Interface_8h.html <https://www.coin-or.org/Doxygen/Clp/Clp__C__Interface_8h.html> — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#205 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABWJYHBZR4EWRRU3V32DYI3UBHZYBANCNFSM5DXOQO5Q>. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[jjhforrest]

Looking at Clp_C_Interface.h Clp_Simplex * alreadySolved and Clp_Simplex *modified Clp_copyinStatus(modified, Clp_statusArray(alreadySolved));

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On 10/09/2021 13:20, Florian Fontan wrote: These methods will cause disk accesses. I would have expected some C/C++ structures to store rather than files to write. Is the best solution to copy the |ClpSimplex| object with the copy constructor and then to modify it? In this case, I can't find the copy constructor in the C interface https://www.coin-or.org/Doxygen/Clp/Clp__C__Interface_8h.html <https://www.coin-or.org/Doxygen/Clp/Clp__C__Interface_8h.html> — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#205 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABWJYHBZR4EWRRU3V32DYI3UBHZYBANCNFSM5DXOQO5Q>. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[fontanf]

Thanks, it seems to be what I was looking for. With the status array, I don't need to have both ClpSimplex in memory at the same time