How can I multiply each element of a cell array, defined as an anonymous function handle?

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Jonas Holfelt 2018-9-26

1
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https://ww2.mathworks.cn/matlabcentral/answers/420807-how-can-i-multiply-each-element-of-a-cell-array-defined-as-an-anonymous-function-handle

评论： Georgios Koutsakis 2019-10-4

I have a cell array FS which contains a function handle at each cell. I want to multiply the output of each cell with each other (giving each function handle the SAME input). The function handles in each cell are identical except for the i value stored in them.

Define array as:

N = 5;
for i=1:N
FS{i} = @(x) x+i;
end

i can obtain my desired result by a simple loop:

x = 3;
P = FS{1}(x)
for i=2:length(FS)
P = P * FS{i}(x)
end

However, I wish to define this operation as a new function handle, performing the same action:

b = @(x) FS{1}(x) * FS{2}(x) * FS{3}(x) ... * FS{N}(x)

but this should of course be flexible for any number of elements (FS).

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采纳的回答

Walter Roberson 2018-9-26

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/420807-how-can-i-multiply-each-element-of-a-cell-array-defined-as-an-anonymous-function-handle#answer_338483

在 MATLAB Online 中打开

b = @(x) prod(cellfun(@(F) F(x), FS))

This assumes that the output of each handle is scalar even if x is non-scalar.

If you really do mean * as in algebraic matrix multiplication, which assumes that the results of each function handle will be either a scalar or a matrix whose number of columns is the same as the number of rows of output of the next function handle (e.g., square matrices work well) then

b = @(x) fold(@mtimes, cellfun(@(F) F(x), FS), 1);