How to evaluate a cell of function handles?

Question

Max 2016-1-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/264214-how-to-evaluate-a-cell-of-function-handles

评论： Max 2016-1-21

采纳的回答： Kirby Fears

在 MATLAB Online 中打开

Hi,

suppose that we have cell arrays of function handles Rnum, for example:

fnum=matlabFunction(y);
Fnum=@(x)integral(fnum,0,x);
Rnum{i,:}=@(x) exp(-(Fnum(x)).^beta_hat(i,:));

with i-number of different beta_hats. y is a function which consists of i-number of symbolic variables.

Now, I would like to evaluate all functions at the points: x = 0:100:4000.

Does anyone know how it works?

PS: If I do it for only one point x = 400, I can use the following code which works very well: cellfun(@(c) c(x),Rnum).

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Answer 1

Kirby Fears 2016-1-20

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在 MATLAB Online 中打开

Max,

If your function handles can accept an array of x values and return an array of results, then your current implementation works fine. It would look like this:

x = 0:100:4000;
resultsCell = cellfun(@(c) c(x),Rnum,'UniformOutput',false);

Otherwise you can use arrayfun or a loop to go over the different x values. A loop might actually be easier to read:

x = 0:100:4000;
resultCell = cell(numel(x),1);
for xval = 1:numel(x),
    resultCell{xval} = cellfun(@(c) c(x(xval)),Rnum);
end

The arrayfun approach would look like this:

resultCell = ...
  arrayfun(@(xval) cellfun(@(c) c(xval),Rnum),x,'UniformOutput',false);

Hope this helps.

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Max 2016-1-21

Hey Kirby, thnx for your solution. Now, it works very well. That´s exactly what I was searching for.

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Answer 2

Rebecca Krosnick 2016-1-20

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/264214-how-to-evaluate-a-cell-of-function-handles#answer_206818

Using the "cellfun" function as you have pointed out is a good way to apply a function to each cell in a cell array.

If you would like to call the function on multiple input points x, then you should either call "cellfun" for each x value, or change your implementation of your function c such that it will take as an argument the vector 0:100:4000 and produces the appropriate results.