How to avoid negative intermediate guess in nlmefit

2 次查看（过去 30 天）

Rui 2014-10-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159058-how-to-avoid-negative-intermediate-guess-in-nlmefit

评论： Rui 2014-10-22

Hello everyone,

when I use nlmefit, it always comes up with some negative guess after a few iterations, these negative values crash my ODE solver. Is there a way to avoid this?

The easiest way I can think of is to set lower bound for fitted parameters, however, I cannot figure out how to do that with nlmefit.

Thank you!

Rui

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。

采纳的回答

Tom Lane 2014-10-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159058-how-to-avoid-negative-intermediate-guess-in-nlmefit#answer_155669

If a parameter P needs to be positive, sometimes people will instead estimate a parameter logP and then use exp(logP) in place of P in their function.