Anonymous function with vector instead of multiple inputs

Question

Stephan 2017-10-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/361611-anonymous-function-with-vector-instead-of-multiple-inputs

评论： Stephan 2017-10-25

Hello everyone,

I have the following example code that creates an array of functions. The size of the array and the number of input arguments varies. I would like to evaluate the functions as explained in the comments in the code.

Thanks for any help,

Stephan

   %
%%Input
N = 3;
%---------- Is this efficiently preallocated? -----------------------------
variables  = cell(N,1); 
fct_handle = cell(N,1); 
myfunction = cell(N,1);
%--------------------------------------------------------------------------
%%Define multidimensional input
for j = 1:N
   variables{j} = sym(sprintf('x_%d',j));
end
%%Define anonymous function
for j = 1:N
   temp = 0;
   for k = 1:N
        temp = temp + variables{k};
   end
   myfunction{j} = temp;
   fct_handle{j} = matlabFunction(myfunction{j});
end
%%Evaluation of function
% I want to evaluate the anonymous functions like this...
input = randn(1,N);
fct_handle{1}(input(1),input(2),input(3));
fct_handle{2}(input(1),input(2),input(3));
fct_handle{3}(input(1),input(2),input(3));
%--------------------- Unforunately this does not work --------------------
for j = 1:N
    fct_handle{j}(input);
end
%--------------------------------------------------------------------------

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Answer 1

David Ding 2017-10-19

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Hi Stephan,

First of all the use of "cell" function is perfectly fine. With regards to the error you are seeing, it is because the way your anonymous function is defined, it expects three input arguments. I understand that you have an input vector which contains three elements. However, you would still need to "split" the elements up when you call the anonymous function. Something like this:

my_anon_func(input(1), input(2), input(3))

Thanks,

David