How to calculate the integral of the complicated functions of function handles in a cell?
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Hi, I stuck for two days. I don't know how to calculate the integral of the sum of function handles in a cell. Please see the below examples:
f{1} = @(x) x;
f{2} = @(x) x^2;
g = @(x) sum(cellfun(@(y) y(x), f));
integral(@(x) g, -3,3);
Error: Input function must return 'double' or 'single' values. Found 'function_handle'.
PS: please don't change the formula, because this is just an example. My real problem is far more complicated than this. It has log and exp of this sum (integral(log(sum), -inf, inf)). So I can't break them up to do the integral individually and sum the integrals.I need to use sum(cellfun). Thank you.
Version: Matlab R2012a
Can anyone help me? Really appreciate.
2 Comments
Accepted Answer
Azzi Abdelmalek
on 1 Apr 2014
f{1} = @(x) x;
f{2} = @(x) x.^2;
g=@(x) f{1}(x)+f{2}(x)
integral(@(x) g(x), -3,3)
3 Comments
Azzi Abdelmalek
on 1 Apr 2014
Edited: Azzi Abdelmalek
on 1 Apr 2014
Maybe there is better. for the moment I have one solution using eval
f{1} = @(x) x;
f{2} = @(x) x.^2;
n=numel(f)
d=['g=@(x)' sprintf('f{%d}(x)+',1:n)]
d(end)=[]
eval(d)
integral(@(x) g(x), -3,3)
More Answers (1)
Sean de Wolski
on 1 Apr 2014
Edited: Sean de Wolski
on 1 Apr 2014
Here's a method that scales:
f{1} = @(x) x;
f{2} = @(x) x.^2;
f{3} = @(x) exp(x)-log(x);
I = sum(cellfun(@(fun)integral(fun,-3,3),f))
Instead of using cellfun to evaluate the functions, use it to evaluate the integral and sum the integrals as Patrik suggested above.
Note you need to vectorize the functions (. before /*^)
3 Comments
Sean de Wolski
on 1 Apr 2014
Huh?
cellfun(@(fun)integral(fun,-3,3),f)
Evaluates the integral over the range for each function in funs. Do with this info as you wish!
Azzi Abdelmalek
on 1 Apr 2014
Smashing, you have to be clear, your question was about the sum. If there is something else, please edit your question and make it precise.
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