Using fzero with two conditions

Question

Ana Carolina da Silva Pacheco 2021-5-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/832653-using-fzero-with-two-conditions

评论： Walter Roberson 2021-5-18

I have a fzero function in which I'm setting an equilibrium equation in terms of a position x, so I can find the value of x. The problem is that I have one more variable as incognita in this equilibrium equation. Also, I have one more equation that could help me. Briefly, I have two equations and two incognitas. I don't know how to write the fzero function in terms of this two equations to find both of the incognitas. Can anybody help me, please?

P.S. my problem requires an interactive procedure.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2021-5-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/832653-using-fzero-with-two-conditions#answer_702113

fzero() cannot be used with two equations or two unknowns.

fsolve() from the Optimization toolbox can be used.

Also, fminsearch() from basic MATLAB can be used, if you rewrite in terms of the square of the function -- in which case the minima of the square would be when the function was zero. However, it is difficult to use fminsearch() with constraints. But in the File Exchange you can find John D'Errico's fminsearchbnd to do an fminsearch with upper and lower bounds.