# How to tell an multi-output anonymous function to vectorize its output components which are constant

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Mohammad Shojaei Arani 2021 年 10 月 16 日
Hello friends,
I have an apparently simple but very annoying problem. Consider the function handle
f=@(x,y) [x+y;2;x*y;x^2-1;3];
When I want to calculate the expression f([1 2],3) then matlab gives an error message ('mismatch between dimensions'). Of course, I can easily fix this problem by re-defining the above function handle as
f=@(x,y) [x+y;2+x-x;x*y;x^2-1;3+x-x];
However, the problem is that my anonymous function is defined whithin a for-loop where I cannot mannually add x-x to the constants plus that
I do not know beforehand which outputs are constant and which are not. The natural way to fix this problem seems to be to update f like
f=@(x,y) f(x,y)+[0;x-x;0;0;x-x];
But, this trick does not work, unfortunately.
It is greatly appreciated if anybody has an idea how to fix this really annoying problem.
Babak Shojaei Arani

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### 採用された回答

Matt J 2021 年 10 月 16 日

One way,
f=@(x,y) completeRows({x+y;2;x*y;x.^2-1;3});
f([1 2],3)
ans = 5×2
4 5 2 2 3 6 0 3 3 3
function out=completeRows(C)
n=max(cellfun('length',C));
for i=1:numel(C)
if isscalar(C{i}), C{i}=repelem(C{i},1,n); end
end
out=cell2mat(C);
end
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Mohammad Shojaei Arani 2021 年 11 月 13 日
Thanks a lot!

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