No current plans – OpenOffice (or is it LibreOffice?) already has the COIN-OR CBC solver integrated into its Solver engine. What features do you particularly want?
I modeled a huge assignment problem. Since I have about 2000 variables i needed another solver than the one provided with excel. I was greatly surprised by how smooth the applicance an the gui are. But: When trying to solve even the smallest parts of my problem, I encountered the same error solution:
“The Servername or the Server adress could not be processed. (at line 6811) (at line 7158) (at line 2816)
Source = msxml3.dll, ErrNumber = – 2147012889”
I ran on a Windows 8.1 Excel 2013 first, then tried on Vista with Excel 2011. Both with the newest OpenSolver 26.
I read the other posts on this topic, but I couldn’t figure out whether it was a Problem with my Setup or a general bug?
Also I tried the standard solver of excel on about 200 variables, it worked fine.
If you mean the open solver; it was Version 2.6, where I tried as well as CBC, gurobi and bonmin. All of them gave me the same Errors. Yesterday I tried solving on a MacBook for a Change OSX 10.10 with Excel for Mac 2011 and the newest (Advanced) OpenSolver for Mac. I tried Gurobi and after 3 Hours of which I thought it was calculating the same Error appeared again.
How can I enable contacting NEOS Servers?
It looks like your access to NEOS may be blocked, and so you cannot reach the NEOS machines using your internet connection. I suggest you try solving using the standard CBC solver on your own machine (or try running at home, perhaps?). Thanks for the feedback; we will use it to improve the error message we generate in this case. Andrew
I would like to thanks the developers for providing such an incredibly powerful tool.
I am using it at Lancaster Environment Centre at Lancaster University (U.K.) for allocation of final year dissertation project supervisors to about 150 students (about 60 supervisors). If you ever tried to please more than one person at a time, you know that pleasing 210 is normally pretty much impossible.
The students submit a list of preferred projects from the list I publish (attached to supervisor names), and the Department give me list of required staff loads. Project and preferences information is collected (from staff and from students) using the Moodle VLE (with an interface kindly set up by our collegaue), I reformulate the data into a binary programming problem, and your OpenSolve does the rest.
You are making 210 persons happy at the same time! This includes me as one of the project supervisors. Thank you!
Thanks for your positive email; I’m really pleased to hear that OpenSolver is proving useful in your student allocation. (We use a Python PuLP optimisation model for the same proces in our department that we will be embedding into SolverStudio at some stage.) Thanks for taking the time to give us your feedback; it is much appreciated. Cheers, Andrew. PS: Other users might be interested in the Moodle interface – are there any links to the code for this?
First let me join the long list of those who would like to thank you for providing us with such a useful and powerful tool.
Now, my question: when using OpenSolver I get a VBA error message “Subscript out of range” (at line 1465) (at line 2810) (ErrNumber=9).
I’m using OpenSolver 2.6 on a French system (and the error message is actually in French).
I tried to track down the origin of the error in VBA debugging mode. The exception is raised by the sub WriteConstraintListToSheet in the class module COpenSolver and more precisely in the code that writes the variable duals. UBound(ReducedCosts) displays 828 but UBound(VarCell) displays only 788. Therefore, the line 1944 fails with i=789.
Other than that, the solution provided by the solver (CBC) seems OK to me.
I have also tried a smaller model. I still get the same error; UBound(VarCell) is 186 and UBound(ReducedCosts) is 330.
Please do you have any idea why this is happening?
Thanks for reporting this (and giving us so much useful detail); it looks like a bug we need to fix. We’ll be in touch if we cannot find the problem without requesting your example spreadsheet. Cheers, and sorry for the inconvenience of this. Andrew
Thanks for the feedback. Please use the “Sensitivity Analysis” section in the Model dialog to generate duals either on the same sheet as the model, or on a stand-alone sheet. Hope this helps, Andrew
I’m building a model with OpenSolver in VBA and I am trying to figure out a way to change the constraints in VBA if there is an error and then run the model with the new constraints. Is there a straight forward way to do this that I’m missing?
When calling `RunOpenSolver` setting the optional argument `MinimiseUserInteraction` to True will suppress all error messages so that your code won’t get interrupted. If an error occurs while solving, `RunOpenSolver` will return `OpenSolverResult.ErrorOccurred`, which you should be able to test for and then change the constraints (using the normal Solver VBA methods). Let us know how you get on.
That is tricky because an infeasible model (i.e. one with no solution) can be caused by a combination of constraints. I suggest you “elasticise” the constraints be adding slack/surplus variables that you penalise in the objective. Then, the solution is always feasible, but may be bad because it uses some slack/surplus variables. Hope this helps. Andrew
Yes. The problem is exactly that. Some of the Decision variables are not copied by from cbu to the excel cella. Everything workshop fine with the standard excel solver. Can I send the xls file to you to check whst the problem is? Thanks again
I’m Josh, a student working on OpenSolver this summer. I believe I’ve been working on your issue: was the sheet that you sent to Andrew named SenHigle.xlsx?
If it is, I suspect that the issue is in your model. In the sheet Foglio1, your first constraint is as follows:
B5, C5 and D5 don’t have ‘Two-stage recourse’! behind them, so the solver is looking at the cells in the ‘Foglio1’ sheet, rather than the cells in the ‘Two-stage recourse’ sheet. You should review the rest of you model for similar errors, I spotted it in at least one other place =)
Hope this is helpful. If this isn’t your issue, please ignore this message.
Hi, I have a problem with opensolver with excel 2013 64 bits. The solution seems correctly computed by cbc but some of the components are not shown in excel. The show model demonstrate that everything is OK. I uickly looked at the discussion forum but I was unable to find any answer. Please help. I can alos email the file showing the problem
Sorry it is not clear to you what’s going on. What do you mean by “but some of the components are not shown in excel”? If you mean that some of the decision variable values are not written to the sheet, then I suspect you may be making a mistake as no-one else has reported this issue. Andrew
I often get into a state that the oversolver – model window will not close if I click Cancel, or the red or alt F4 … nothing works. I have to kill excel with task manager to recover. Any help?
Jeff, This sounds like the RefEdit add-in not working. This is the one where you type in a cell range, or click on a sheet have the range appear. I am sorry you are facing these problems. RefEdit is known to be tricky to use, and somewhat unreliable, but we could not get by without using it. You could try repairing your Excel installation, in the hope that this may fix it. If not, then if you can give us a repeatable sequence of steps to make it crash, then we’d love to look into it. Note, however, that we have already spent many many hours working around RefEdit glitches – OpenSolver very seldom crashes on us now, but clearly your experience is different, and so perhaps there is an outstanding issue we can fix. Thanks for making contact; I look forward to hearing from you. Andrew
Hi, i’ve tryied put all the files in the archive but without success.
This is the message i get:
”
OpenSolver26 Error
OpenSolver2.6 encountered an erro:
The CBC solver did not complete, but aborted with the error code 1.
The last log file can be viewed under OpenSolver menu and may give you more information on what caused this error.(at line 1580)(at line 1448)(at line 2810)
Source = OpenSolver Model Solving Locally, ErrNumber=-2147220503
Please post the details on CBC and “OpenSolverFile” from your About OpenSolver dialog so we can see what’s going on. Also, please check to see if the .zip file is marked as “Blocked” under Properties, in which case please follow the “unblock” steps outlined at http://solverstudio.org/download-install/ Thanks, Andrew
We need to see the details from the About OpenSolver dialog that shows the locations of OpenSolver and CBC, eg
CBC 64-bit v2.8.8 at D:\Documents\Projects\OpenSolver\OpenSolver-Master\OpenSolver-master\Solvers\win64\cbc.exe
and the OpenSolverFile location (which I’m sorry you cannot copy/paste from the dialog, and so you will need to type in).
Please remove the non-ASCII characters from the folder name… stick with a to z, A to Z, in the US alphabet. VBA does not like unicode. Please let hs know if it works. Andrew
Can you please send me the details from the About OpenSolver dialog, including all the file locations? And, have you tried putting the OpenSolver folder (with all files as downloaded) in your Documents folder? Andrew
The bonmin and couenne NLP algorithms do not recognize the function ‘sumif()’ and crash as a result. This means that these algorithms cannot be used to solve nonlinear shortest path or min-cost-flow optimization problems.
Thanks for reminding us of this. sumif() is tricky to code up, and so we have not done it yet. But it is on our todo list. In the meantime, I suggest formulations that avoid sumif(), or using NOMAD. Cheers, Andrew
I’m using the CBC linear solver to solve an optimization problem very much like the demand/production model in the youtube video in your help file. When I run it, the Solver successfully solves the LP. But the solution it provides is nowhere near the optimal solution. I was easily able to nearly double my objective function by adding constraints (to force cells with the highest coefficients to produce their maximum). Is there some parameter I need to set — either in OpenSolver directly, or in the CBC parameters, to force the optimizer to keep working past its first feasible solution?
I am also having this problem, and I’m also using Mac Excel 2011, maybe this problem is specific to that. It only happens when I try to run a sensitivity analysis.
This is a problem we’ve had with Excel 2011 where it will sometimes show an irrelevant error message in place of the original error. In this case the error it is overwriting is one saying that it can’t do a sensitivity analysis due to binary/integer constraints. If you remove these constraints, you should be able to get the dual values without problems, let me know if not.
We have a new, more robust error system coming in the next OpenSolver release very soon that should fix this annoying problem!
Are you planning on adding support for LibreOffice and/or Apache OpenOffice?
No current plans – OpenOffice (or is it LibreOffice?) already has the COIN-OR CBC solver integrated into its Solver engine. What features do you particularly want?
Hello dear OpenSolver Team
I modeled a huge assignment problem. Since I have about 2000 variables i needed another solver than the one provided with excel. I was greatly surprised by how smooth the applicance an the gui are. But: When trying to solve even the smallest parts of my problem, I encountered the same error solution:
“The Servername or the Server adress could not be processed. (at line 6811) (at line 7158) (at line 2816)
Source = msxml3.dll, ErrNumber = – 2147012889”
I ran on a Windows 8.1 Excel 2013 first, then tried on Vista with Excel 2011. Both with the newest OpenSolver 26.
I read the other posts on this topic, but I couldn’t figure out whether it was a Problem with my Setup or a general bug?
Also I tried the standard solver of excel on about 200 variables, it worked fine.
Thank you for your assistance.
Fabian
This looks like an error trying to contact the NEOS servers; perhaps your PC cannot access them. Please confirm what solver you were using?
If you mean the open solver; it was Version 2.6, where I tried as well as CBC, gurobi and bonmin. All of them gave me the same Errors. Yesterday I tried solving on a MacBook for a Change OSX 10.10 with Excel for Mac 2011 and the newest (Advanced) OpenSolver for Mac. I tried Gurobi and after 3 Hours of which I thought it was calculating the same Error appeared again.
How can I enable contacting NEOS Servers?
Thanks for your Help.
It looks like your access to NEOS may be blocked, and so you cannot reach the NEOS machines using your internet connection. I suggest you try solving using the standard CBC solver on your own machine (or try running at home, perhaps?). Thanks for the feedback; we will use it to improve the error message we generate in this case. Andrew
I would like to thanks the developers for providing such an incredibly powerful tool.
I am using it at Lancaster Environment Centre at Lancaster University (U.K.) for allocation of final year dissertation project supervisors to about 150 students (about 60 supervisors). If you ever tried to please more than one person at a time, you know that pleasing 210 is normally pretty much impossible.
The students submit a list of preferred projects from the list I publish (attached to supervisor names), and the Department give me list of required staff loads. Project and preferences information is collected (from staff and from students) using the Moodle VLE (with an interface kindly set up by our collegaue), I reformulate the data into a binary programming problem, and your OpenSolve does the rest.
You are making 210 persons happy at the same time! This includes me as one of the project supervisors. Thank you!
Thanks for your positive email; I’m really pleased to hear that OpenSolver is proving useful in your student allocation. (We use a Python PuLP optimisation model for the same proces in our department that we will be embedding into SolverStudio at some stage.) Thanks for taking the time to give us your feedback; it is much appreciated. Cheers, Andrew. PS: Other users might be interested in the Moodle interface – are there any links to the code for this?
Hi Andrew,
First let me join the long list of those who would like to thank you for providing us with such a useful and powerful tool.
Now, my question: when using OpenSolver I get a VBA error message “Subscript out of range” (at line 1465) (at line 2810) (ErrNumber=9).
I’m using OpenSolver 2.6 on a French system (and the error message is actually in French).
I tried to track down the origin of the error in VBA debugging mode. The exception is raised by the sub WriteConstraintListToSheet in the class module COpenSolver and more precisely in the code that writes the variable duals. UBound(ReducedCosts) displays 828 but UBound(VarCell) displays only 788. Therefore, the line 1944 fails with i=789.
Other than that, the solution provided by the solver (CBC) seems OK to me.
I have also tried a smaller model. I still get the same error; UBound(VarCell) is 186 and UBound(ReducedCosts) is 330.
Please do you have any idea why this is happening?
Thanks again,
Roman
Thanks for reporting this (and giving us so much useful detail); it looks like a bug we need to fix. We’ll be in touch if we cannot find the problem without requesting your example spreadsheet. Cheers, and sorry for the inconvenience of this. Andrew
A great and simple tool.
Could you give me some indication on how to actívate printing of shadow prices for last versión of Open Solver?
Thank you
Thanks for the feedback. Please use the “Sensitivity Analysis” section in the Model dialog to generate duals either on the same sheet as the model, or on a stand-alone sheet. Hope this helps, Andrew
Hi,
I’m building a model with OpenSolver in VBA and I am trying to figure out a way to change the constraints in VBA if there is an error and then run the model with the new constraints. Is there a straight forward way to do this that I’m missing?
Thanks,
-Greg
Hi Greg,
When calling `RunOpenSolver` setting the optional argument `MinimiseUserInteraction` to True will suppress all error messages so that your code won’t get interrupted. If an error occurs while solving, `RunOpenSolver` will return `OpenSolverResult.ErrorOccurred`, which you should be able to test for and then change the constraints (using the normal Solver VBA methods). Let us know how you get on.
Cheers,
Jack
That is tricky because an infeasible model (i.e. one with no solution) can be caused by a combination of constraints. I suggest you “elasticise” the constraints be adding slack/surplus variables that you penalise in the objective. Then, the solution is always feasible, but may be bad because it uses some slack/surplus variables. Hope this helps. Andrew
Thanks for looking at my problem. I will try to modify the file according to your suggestions and I will let you know
Yes. The problem is exactly that. Some of the Decision variables are not copied by from cbu to the excel cella. Everything workshop fine with the standard excel solver. Can I send the xls file to you to check whst the problem is? Thanks again
Hi Renato
I’m Josh, a student working on OpenSolver this summer. I believe I’ve been working on your issue: was the sheet that you sent to Andrew named SenHigle.xlsx?
If it is, I suspect that the issue is in your model. In the sheet Foglio1, your first constraint is as follows:
\ ‘Two-stage recourse’!$N$11 = ‘Two-stage recourse’!$P$11 +1 B5 +1 C5 +1 D5 = +2
B5, C5 and D5 don’t have ‘Two-stage recourse’! behind them, so the solver is looking at the cells in the ‘Foglio1’ sheet, rather than the cells in the ‘Two-stage recourse’ sheet. You should review the rest of you model for similar errors, I spotted it in at least one other place =)
Hope this is helpful. If this isn’t your issue, please ignore this message.
Cheers
Josh
Hi, I have a problem with opensolver with excel 2013 64 bits. The solution seems correctly computed by cbc but some of the components are not shown in excel. The show model demonstrate that everything is OK. I uickly looked at the discussion forum but I was unable to find any answer. Please help. I can alos email the file showing the problem
Sorry it is not clear to you what’s going on. What do you mean by “but some of the components are not shown in excel”? If you mean that some of the decision variable values are not written to the sheet, then I suspect you may be making a mistake as no-one else has reported this issue. Andrew
Yes, please email it to a dot mason at auckland dot ac dot nz. Thanks, Andrew
I often get into a state that the oversolver – model window will not close if I click Cancel, or the red or alt F4 … nothing works. I have to kill excel with task manager to recover. Any help?
Jeff, This sounds like the RefEdit add-in not working. This is the one where you type in a cell range, or click on a sheet have the range appear. I am sorry you are facing these problems. RefEdit is known to be tricky to use, and somewhat unreliable, but we could not get by without using it. You could try repairing your Excel installation, in the hope that this may fix it. If not, then if you can give us a repeatable sequence of steps to make it crash, then we’d love to look into it. Note, however, that we have already spent many many hours working around RefEdit glitches – OpenSolver very seldom crashes on us now, but clearly your experience is different, and so perhaps there is an outstanding issue we can fix. Thanks for making contact; I look forward to hearing from you. Andrew
Hi, i’ve tryied put all the files in the archive but without success.
This is the message i get:
”
OpenSolver26 Error
OpenSolver2.6 encountered an erro:
The CBC solver did not complete, but aborted with the error code 1.
The last log file can be viewed under OpenSolver menu and may give you more information on what caused this error.(at line 1580)(at line 1448)(at line 2810)
Source = OpenSolver Model Solving Locally, ErrNumber=-2147220503
“
Please post the details on CBC and “OpenSolverFile” from your About OpenSolver dialog so we can see what’s going on. Also, please check to see if the .zip file is marked as “Blocked” under Properties, in which case please follow the “unblock” steps outlined at http://solverstudio.org/download-install/ Thanks, Andrew
about open solver:
6092 Err.Raise Err.Number, Err.Source, Err.Description & IIf(Erl = 0, “”, ” (at line ” & Erl & “)”)
is that it?????
We need to see the details from the About OpenSolver dialog that shows the locations of OpenSolver and CBC, eg
CBC 64-bit v2.8.8 at D:\Documents\Projects\OpenSolver\OpenSolver-Master\OpenSolver-master\Solvers\win64\cbc.exe
and the OpenSolverFile location (which I’m sorry you cannot copy/paste from the dialog, and so you will need to type in).
C:\Rossignolo\otimização de sistemas\OpenSolver26_AdvancedWin\Solvers\win64\cbc.exe
Please remove the non-ASCII characters from the folder name… stick with a to z, A to Z, in the US alphabet. VBA does not like unicode. Please let hs know if it works. Andrew
i’m using win 8.1 isn’t it the problem?
i saw that the cbc is tested stable until win 7 at this site
http://www.coin-or.org/projects/Cbc.xml
I’ve tryied from the easiest model to the hardest and none of them executes.
I always get this message:
“OpenSolver2.6 encoutered an error:
The CBC Solver did not complete, but aborted with error code 1.
error (at line 1580)(at line 1448)(at line 2810)
Source = OpenSolver Model Solving Locally, ErrNumber= -2147220503
“
Can you please send me the details from the About OpenSolver dialog, including all the file locations? And, have you tried putting the OpenSolver folder (with all files as downloaded) in your Documents folder? Andrew
I’m using 2.1 and it’s working perfect.
The bonmin and couenne NLP algorithms do not recognize the function ‘sumif()’ and crash as a result. This means that these algorithms cannot be used to solve nonlinear shortest path or min-cost-flow optimization problems.
Thanks for reminding us of this. sumif() is tricky to code up, and so we have not done it yet. But it is on our todo list. In the meantime, I suggest formulations that avoid sumif(), or using NOMAD. Cheers, Andrew
I’m using the CBC linear solver to solve an optimization problem very much like the demand/production model in the youtube video in your help file. When I run it, the Solver successfully solves the LP. But the solution it provides is nowhere near the optimal solution. I was easily able to nearly double my objective function by adding constraints (to force cells with the highest coefficients to produce their maximum). Is there some parameter I need to set — either in OpenSolver directly, or in the CBC parameters, to force the optimizer to keep working past its first feasible solution?
what does this mean : method ‘solvemodel’ of object ‘copensolver’ failed (at line 2810)
source = opensolver, errnumber = -2147220503
(MAC excel 2011)
We will have a look into this. Sorry about the problem. Andrew
I am also having this problem, and I’m also using Mac Excel 2011, maybe this problem is specific to that. It only happens when I try to run a sensitivity analysis.
This is a problem we’ve had with Excel 2011 where it will sometimes show an irrelevant error message in place of the original error. In this case the error it is overwriting is one saying that it can’t do a sensitivity analysis due to binary/integer constraints. If you remove these constraints, you should be able to get the dual values without problems, let me know if not.
We have a new, more robust error system coming in the next OpenSolver release very soon that should fix this annoying problem!
Thanks,
Jack