costly anonymous function declaration for solving a equation system with parameters

Question

dominik 2013-12-5

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https://ww2.mathworks.cn/matlabcentral/answers/108753-costly-anonymous-function-declaration-for-solving-a-equation-system-with-parameters

评论： dominik 2013-12-9

Hi i have to solve a equation system (which is a matlab functiion)for many parameters values, so i run a loop over the parameter values, then use an anonymous function to pass the parameters to the equation system, then use fsolve to solve this anonymous function. now i understand that solving takes some time, but setting up the anonymous function takes almost the same time. why? can this be done faster?

The script looks like this

for i=1:ni
   parameters= par_fun(i);
   my_anon_fun = @my_fun(x)(x,parameters);
   [sol fval exitflag]= fsolve(my_anon_fun,starval);
end

where my_fun is the eqauation system and par_fun give the parameter vector for the equation system. The profiler shows a lot of time spent in the line my_an_fun = @myfun(x)(x,parameters);

Thanks Dominik

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Walter Roberson 2013-12-5

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Does your line perhaps instead look like

my_anon_fun = @(x) my_fun(x,parameters);

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Answer 1

Alan Weiss 2013-12-5

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https://ww2.mathworks.cn/matlabcentral/answers/108753-costly-anonymous-function-declaration-for-solving-a-equation-system-with-parameters#answer_117439

Perhaps it would be faster for you to use nested functions rather than anonymous functions. I think (thought I haven't tested this idea) that this would avoid the overhead of creating anonymous functions.

Alan Weiss

MATLAB mathematical toolbox documentation