speed for loop in sum

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Ole
Ole 2019-3-11
评论： Ole 2019-3-11
Can the for loop be removed ?
x=linspace(-2,2,100); %some vector
[X,XX]=meshgrid(x,x); %some matrix
a=1/2;%some constant
A0=zeros(size(X));%initialize the sum
A0k = @(k,X,a)(((-1)^k).*((X./a).^(2*k)).*besselj(2*k,X));%series
for l=0:20
A0 = A0+A0k(l,X,a); %sum of series
end
  2 个评论
Torsten
Torsten 2019-3-11
编辑：Torsten 2019-3-11
What's the problem with the solution I gave ?
Ole
Ole 2019-3-11
I was not able to make it work.

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采纳的回答

Torsten
Torsten 2019-3-11
function main
x = linspace(-2,2,100); %some vector
[X,XX] = meshgrid(x,x); %some matrix
k = 0:20;
a = 0.5;
A0 = arrayfun(@(x)sum((-1).^k.*(x/a).^(2*k).*besselj(2*k,x)),X)
end
  1 个评论
Ole
Ole 2019-3-11
Thank you!
just as feedback the arrayfun is slower than the loop.
0.096s for the for loop
0.30s for the arrayfun

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