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

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.

Thanks in advance

Babak Shojaei Arani

Answer 1

[Matt J]

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

[Mohammad Shojaei Arani]

Thanks a lot!