How to vectorize a complex function?

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Mohammad Shojaei Arani
Mohammad Shojaei Arani on 23 Nov 2022
Answered: Paul on 23 Nov 2022
Hello,
I have a rather complex function but I need to vectorize it in order to be able to use a matlab optimization package. My function is
g=@(par) nonbcon(par,J,N,X0,X,EZ,H,H_coeff,Coeff,knots,mesh_fine,M,SplineType,w);
You do not need to know the details of this function. g, accepts a row vector "par" and then as output gives either 0 or 1. However, I need to vectorize g so that it accepts a matrix A and performs the same operation on each row of A. I tried to use arrayfun but it is a bit complicated for me. I need something like the following (of course, this is wrong):
G=@(y)arrayfun(@(x) nonbcon(x),y(i,:));
but, I do not know how to modify G to do the job for me.
Any idea?
Thanks in advance!
Babak
  4 Comments
Mohammad Shojaei Arani
Mohammad Shojaei Arani on 23 Nov 2022
OK. Thanks!
It seems that my only option is to use for-loop as this is not aparently paralaleisable

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Answers (1)

Paul
Paul on 23 Nov 2022
Hi Babak,
Here is a one line solution. Whether or not it's more efficient/effective/clearer than the loop is an open question.
Test data for input
rng(101);
test = rand(4,3);
sum(test,2)
ans = 4×1
1.9232 1.5945 0.8897 1.4173
Function that accepts a row vector and returns 0 or 1
g = @(par) double(sum(par,2)>1);
Loop solution
r1 = zeros(4,1);
for ii = 1:4,
r1(ii) = g(test(ii,:));
end
r1
r1 = 4×1
1 1 0 1
One line solution
r2 = cellfun(g,mat2cell(test,ones(size(test,1),1)))
r2 = 4×1
1 1 0 1

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