vectorisation a for loop

Question

0 个投票

c=5; 
retint=0; 
dist=log([10:-1:1]+retint); 
for i=1:length(dist)
    eta=exp(-c*abs(dist(i)-dist)); 
    discrim(i)=1/sum(eta);
end

Does anyone know how to vectorise this for loop to make it more efficient?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Stephen23 2019-12-8

Because you are not concatenating anything, square brackets are not needed here:

dist=log((10:-1:1)+retint);

Answer 1

David Hill 2019-12-8

0 个投票

Although arrayfun is really a loop,

c=5; 
retint=0; 
dist=log([10:-1:1]+retint);
discrim=arrayfun(@(x)1/sum(exp(-c*abs(dist-x))),dist);

Answer 2

Stephen23 2019-12-8

0 个投票

Real vectorized code (no loop or arrayfun):

eta = exp(-c*abs(bsxfun(@minus,dist,dist(:))));
discrim = 1./sum(eta,1)

Or for MATLAB versions >=R2016b:

eta = exp(-c*abs(dist-dist(:)));
discrim2 = 1./sum(eta,1)