Same functionality as Excel Solver to set objective to a value

2012 6 7
2 个回答
回答已采纳
5 次查看（30 天）

0 个投票

Hi all
I am currently going through a process of taking an existing calculation perfomed within Excel and transferring it to MATLAB. Part of the existing calculation is to use Excel Solver to optimise two factors to allow a value to be calculated which matches a target value. This was achieved in the Excel solver by setting the objective to a fixed value using the 'Value Of' input box.
Going through the MATLAB optimisation functions I can only find solutions to minimise the value. My question is what function would I use to target a value? Note that I do not have the optimisation toolbox installed.
Many Thanks
Peter

请先登录，再回答此问题。

 采纳的回答

Alan Weiss
Alan Weiss 2012-6-7

0 个投票

I am not sure I understand your question. If you have a single function of a single variable, you can use fzero to solve for f(x) = a, by solving for a zero of the function f(x) - a.
However, you seem to have a single function of two variables, or perhaps you have two functions of two variables. If you have two functions of two variables, use fsolve to find a solution. If you have a single function of two variables, I don't understand what you or Excel can do to find a solution, because in general there are multiple solutions.
And I do not recommend using abs in Optimization Toolbox functions, this introduces unnecessary nonsmoothness. Use a square if you need to (but you probably do not need to).
Alan Weiss
MATLAB mathematical toolbox documentation

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Peter
Peter 2012-6-7
It is two functions and both use the same factors which I need to optimise. It sounds like I need to use fsolve. Thanks for both your help today.

请先登录，再进行评论。

更多回答（1 个）

Titus Edelhofer
Titus Edelhofer 2012-6-7

0 个投票

Hi Peter,
to optimize a variable to be of value XTarget, you need to minimize the function
abs(x - XTarget)
If you don't have restrictions, you can use fminsearch as solver.
Titus

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Peter
Peter 2012-6-7
Thanks for the quick response Titus.
The existing spreadsheet I am using has a column of values (y) and a corresponding distance (x). Depending on the x location, y is either multiplied by Factor1 or Factor2. Another column of values (z) is calculated by multiplying the factored y value by the local distance x. The y and z values are then integrated and their totals are compared to a target value for both results.
Currently in the Excel solver the objective is set to the Y total cell. It has been set to match a target value by changing the cells containing the values for Factor 1 and 2. The constraint which was set is the z total value matches its target value.
With the constraints of matching the z total with a matching value, would I require another solver when using your suggestion of abs(x-Xarget) to find a minimum?

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Solver Outputs and Iterative Display 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by