Indexing cannot yield multiple results error

Hello! I have this function:

function [E1x,E2x]=coupler(Eax,Ebx,Npt1)
n=1;
Eout=zeros(Npt1,2);
E1x=zeros(Npt1,1);
E2x=zeros(Npt1,1);
while n<=Npt1
Enew=[Eax(n); Ebx(n)];
c=[sqrt(0.5) 1i*sqrt(0.5);1i*sqrt(0.5) sqrt(0.5)];
Eout(n,:)=c*Enew;
E1x(n)=Eout(n,1);
E2x(n)=Eout(n,2);
n=n+1;
end
end

I am calling this function like this:

[E11x,E22x] = coupler(Eaf1,Ebf1,Npt);

However the error appears: Indexing cannot yield multiple results. What am I doing wrong?

Best regards, João

[Adam]

Please use the {} Code block, selecting all your code first and clicking it, for more readable formatting.

Does the error tell you which line is causing the problem or have you stepped through the code to determine which line?

I can't see anything at a glance that would cause that error unless you have a variable called 'coupler' in which case the error would make sense as trying to index into a variable cannot give two outputs in the line:

[E11x,E22x] = coupler(Eaf1,Ebf1,Npt);

so make sure you do not have a variable stamping on your function name.

[Star Strider]

...and the best way to detect that possibility is to type:

which coupler -all

in the Command Window. Your function should be the only result you get.

[Joao]

Yes i had another variable called coupler. Many thanks!!

[Adam]

I'll add it as an answer then in case anyone comes to this thread in future with the same problem. I didn't want to put it as an answer first since I wasn't 100% sure if that was the problem.

Answer 1

[Adam]

Check that you do not also have a variable called 'coupler' which will stop Matlab from being able to see your function.

If you have a variable, 'coupler', then the line:

[E11x,E22x] = coupler(Eaf1,Ebf1,Npt);

will attempt to index into that variable, rather than calling your function, which will result in the error you showed as indexing into a variable cannot return two outputs.

As Star Strider points out, you can type:

which coupler -all

to check if you have a variable called 'coupler'. If you get a variable returned here as well as your function then that is the problem.

[Star Strider]

Joao replied:

‘Yes i had another variable called coupler. Many thanks!!’

Answer 2

[BHANESH BHADRECHA]

That is because you have created any loop and in that loop variable is changing its value every time loop executes.

The best way is to clear variables that are defined in that loop.

clear this variables before the loop ends.....

for example

for i=1:1000 j=stft(x); k=max(j); clear j; clear k; end