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Fri, 23 May 2008 00:45:00 GMT, 3 comments.

Hi,

When I try to change the number of solver iterations I can't seem to

actually get it to do more than about 5. I walked through the iterations

step-by-step and after about 5 iterations it quits. If I start from that

solution a couple more times it gets to the solution, so I seem to have a

simple problem that only requires about 15 iterations but changing the number

of iterations allowed doesn't seem to have an effect. I have tried

everything that seems obvious.

Thanks.

http://excel.questionfor.info/wap_q_microsoft-excel_415912.html

tags: excel, iterations, iterations-how, microsoft, msdn, number, software, solver, walked

- In Help, under "Troubleshoot Solver," there are a number of reasons
why Solver might stop prematurely. For instance, "For problems with

integer constraints, you need to decrease the Tolerance setting in the

Solver Options dialog box so that Solver can find a better integer

solution."

If that example isn't the problem, you might want to peruse the

others.

Mark Lincoln

On Sep 27, 3:04 pm, Rick Hicks <Rick Hi....excel.questionfor.info.discussions.microsoft.com>

wrote:

> Hi,

> When I try to change the number of solver iterations I can't seem to

> actually get it to do more than about 5. I walked through the iterations

> step-by-step and after about 5 iterations it quits. If I start from that

> solution a couple more times it gets to the solution, so I seem to have a

> simple problem that only requires about 15 iterations but changing the number

> of iterations allowed doesn't seem to have an effect. I have tried

> everything that seems obvious.

> Thanks.

- If it quits, then Solver cannot improve the solution or it converges on a
value. Have you played with all the options in Solver? Have you decreased

the convergence?

Otherwise, perhaps you really are at the optimal value. I've found that

when setup correctly, Solver is pretty darn accurate. With all due respect

to PivotTables, I believe Solver is the most powerful and useful tool (at

least to us engineers).

Matthew Pfluger

"Rick Hicks" wrote:

> Hi,

> When I try to change the number of solver iterations I can't seem to

> actually get it to do more than about 5. I walked through the iterations

> step-by-step and after about 5 iterations it quits. If I start from that

> solution a couple more times it gets to the solution, so I seem to have a

> simple problem that only requires about 15 iterations but changing the number

> of iterations allowed doesn't seem to have an effect. I have tried

> everything that seems obvious.

> Thanks.

- Thanks,
I found the problem in the troubleshooting. I didn't know if it was

something I would find there or if it was a trick that one of you experts

would know (the first time I trolled this site the result to my problem was a

clever little wrinkle). It turns out I got tired of looking right before I

got to it.

For anyone else stumbling onto this thread in the future, the problem I was

seeing was a "...could not find a feasible solution" message after a few

iterations. The solver would eventually work if I redid it a few times,

restarting with the previous run's results for my variables.

The solution was to check the "Use automatic scaling" box. I have a problem

where my variables range from 1 mil to 10 mil and when I start with all of

them at zero the range is too wide for the solver to deal with.

Thanks again for the help. Know there wasn't a special "trick" helped a lot.

Rick

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