Why is matlabFunction so slow?

Question

Sujit Nair 2011-7-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12491-why-is-matlabfunction-so-slow

移动：Dyuman Joshi 2024-4-6

For example, the following code

%%%%%%%%%
test = sym(zeros(150,150));
fhandle = matlabFunction(test);
%%%%%%%%%

takes about 26 seconds! Is there any way to speed this routine?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Walter Roberson 2019-2-8

For whatever it is worth, on my late 2013 iMac running R2018b, the above takes less than 8 seconds.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Jan 2011-7-27

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12491-why-is-matlabfunction-so-slow#answer_17076

What a funny question.

Of course the runtime depends on the matlabFunction. So please post its code. Otherwise there is absolutely no chance that we can guess where the function could be accelerated.

3 个评论
显示 1更早的评论隐藏 1更早的评论

Jan 2011-7-27

移动：Dyuman Joshi 2024-4-6

You got me. There is in fact a MATLAB function which is called matlabFunction. Sorry, I do not have the Symbolic toolbox.

Daniel Shub 2011-7-27

移动：Dyuman Joshi 2024-4-6

I have the symbolic toolbox and I could not find the function. I tried

>> matlabFunction

??? Undefined function or variable 'matlabFunction'.

and assumed it was not a function. Of course I should have done

>> which -all matlabFunction

/usr/local/matlab/r2011a/toolbox/symbolic/symbolic/@sym/matlabFunction.m % sym method

请先登录，再进行评论。

Answer 2

Giovanni 2011-7-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12491-why-is-matlabfunction-so-slow#answer_17118

I have used matlabFunction for relatively complicated formulas and it doesn't seem too slow. Your example is unrealistic and I don't know exactly how Matlab would process it and why it takes so long. Can you post the actual function you are trying to create a handle out of? That way we might be able to help!

4 个评论
显示 2更早的评论隐藏 2更早的评论

Qt1 Dlmr 2019-2-8

Is tere any way to know where it is in this process at some point (callback or something..) ?

Because I just would like to know it is going to take hours or 10^80 years at the moment...

Walter Roberson 2019-2-8

Unfortunately there is no way to know how far matlabFunction has progressed. The key work is done inside of MuPAD. If you know what you are looking for inside matlabFunction.m then you can tell the difference between it spending time generating the initial code, versus it spending time optimizing the code (which only happens with 'File' output), but both of those are MuPAD calls that you cannot see into.

请先登录，再进行评论。