How to use arrayfun with a function having two vector arguments?

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I have a function f(W,x), where W is a matrix and x is a vector. I would like to use arrayfun to calculate the f(W,x) for several x but constant/fix W. What is the syntax?

Accepted Answer

Andrei Bobrov
Andrei Bobrov on 18 Oct 2016
Edited: Andrei Bobrov on 18 Oct 2016
fW = @(x) f(W, x);
out = cellfun(fW,{x1,x2,x3},'un',0);

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More Answers (2)

Rani V.S
Rani V.S on 18 Oct 2016
A = arrayfun(FUN, B, C, ...) evaluates FUN using elements of arrays B,
C, ... as input arguments. The (I,J,...)th element of A is equal to
FUN(B(I,J,...), C(I,J,...), ...). B, C, ... must all have the same size.

Guillaume on 18 Oct 2016
%W = [.,.,.;.,.,.;.,.,.]; %matrix
%x = [.,.,.,.,.,.]; %vector
result = arrayfun(@(xelem) f(W, xelem), x); %possibly with 'UniformOutput', false, if f output is not scalar
Or if you want to be more explicit
%W = [.,.,.;.,.,.;.,.,.]; %matrix
%x = [.,.,.,.,.,.]; %vector
fW = @(x) f(W, x); %W must exists before this line. Changing W after this line will not affect fW
result = arrayfun(fW, x);
In either case you're creating a new function (with no name in the first case, fW in the second) that binds the matrix W to f and still takes x as an input. You're then using that function in arrayfun to apply it to each element of x.
Guillaume on 18 Oct 2016
Well, first you shouldn't have numbered variables x1, x2, etc. Instead you should have just one variable which is a cell array of vectors. In that case, use cellfun:
x = {x1, x2, x3}; %you really shouldn't create the xi to start with. Put their content in the cell array as you create it.
result = cellfun(@(xv) f(W, xv), x, 'UniformOutput', false);

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