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

Question

Mohammad Shojaei Arani 2021-10-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1565231-how-to-tell-an-multi-output-anonymous-function-to-vectorize-its-output-components-which-are-constant

评论： Mohammad Shojaei Arani 2021-11-13

采纳的回答： Matt J

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

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Matt J 2021-10-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1565231-how-to-tell-an-multi-output-anonymous-function-to-vectorize-its-output-components-which-are-constant#answer_810021

编辑：Matt J 2021-10-16

在 MATLAB Online 中打开

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