Library function log10 not found when using fit

Question

0 个投票

I have been trying to fit some data using a lograthimic fit with the following command, where ind_array and sample_array are my x and y data respectively:

expo_curve=fit(ind_array,sample_array,'log10');

However, I keep getting the following error:

Library function log10 not found.

The weird thing is I was using this exact code like 3 weeks ago and was able to generate the fit. So I am unsure what is going wrong, and the API says that 'log10' is a valid fittype for the fit command.

Any help would be appreciated,

Thank you,

Sean

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。

Follow Question

Answer 1

John D'Errico 2024-5-23

编辑：John D'Errico 2024-5-23

在 MATLAB Online 中打开

1 个投票

x = rand(10,1);y = x + rand(10,1);
fit(x,y,'log10')
ans = 
     Linear model Log10:
     ans(x) = a*log10(x) + b
     Coefficients (with 95% confidence bounds):
       a =      0.5735  (0.1061, 1.041)
       b =       1.279  (0.9743, 1.584)

It is almost always, ALWAYS the case that when this happens, you were previously using a different, more recent MATLAB release.

As you can see above, it does work. But, to be honest, I did not recall that being one of the valid fit types. So I tried it on my computer, and it failed, using R2023a.

And that means they just introduced that option. So you were possibly using an online MATLAB, or a new release on some other computer. But today, you were using an older release, and the option did not exist then. They must have alloed that option in only the last year. I could check the release notes, but I am sure that is the case.

What can you do? Well, make sure your version is a sufficiently recent one. Otherwise, you could use a custom fittype of that form. For example, this would work, even in an older release:

mdl = fittype('a*log10(x) + b',indep = 'x')
mdl = 
     General model:
     mdl(a,b,x) = a*log10(x) + b
fittedmdl = fit(x,y,mdl)
Warning: Start point not provided, choosing random start point.
fittedmdl = 
     General model:
     fittedmdl(x) = a*log10(x) + b
     Coefficients (with 95% confidence bounds):
       a =      0.5735  (0.1061, 1.041)
       b =       1.279  (0.9743, 1.584)

Note that because the model is actually linear in the parameters, fit was smart enough to not bother needing starting values for the 'log10' option.

3 个评论
显示 1更早的评论隐藏 1更早的评论

John D'Errico 2024-5-23

Been there, done that. I tend to keep old releases around, only discarding them when they get 4 or 5 deep. Sometimes it is useful to have an older one, to test some code that someone has an issue with. But the problem is I sometimes end up using one of the older ones by accident.

Steven Lord 2024-5-23

The Release Notes confirm that the ability to specify logarithmic fit types was introduced in Curve Fitting Toolbox in release R2023b.

请先登录，再进行评论。

Answer 2

Kunal Kandhari 2024-5-22

在 MATLAB Online 中打开

0 个投票

Since it worked previously, you may have a path problem.

Run these from a script or your Command Window:

restoredefaultpath
rehash toolboxcache
rehash path
savepath

Then run your code again.

2 个评论
显示无隐藏无

Sean Morgan 2024-5-23

编辑：Sean Morgan 2024-5-23

Thanks for the help,

Unfortuneatly I am still getting the same error after doing what you suggested. Do you have any other ideas?

Also, this is probably related, but I don't seem to have a logarithmic fit type in the curve fitting app either (see screenshot).

Thanks,

Sean

John D'Errico 2024-5-23

No. That would never be a path issue.

请先登录，再进行评论。

Library function log10 not found when using fit

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

3 个评论
显示 1更早的评论隐藏 1更早的评论

更多回答（1 个）

2 个评论
显示无隐藏无

类别

产品

版本

标签

Community Treasure Hunt

Library function log10 not found when using fit

0 个评论 显示 -2更早的评论 隐藏 -2更早的评论

采纳的回答

3 个评论 显示 1更早的评论 隐藏 1更早的评论

更多回答（1 个）

2 个评论 显示 无 隐藏 无

类别

产品

版本

标签

另请参阅

Community Treasure Hunt

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

3 个评论
显示 1更早的评论隐藏 1更早的评论

2 个评论
显示无隐藏无