Passing array arguments to an anonymous function

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Leo Simon
Leo Simon 2013-2-26
I have an anonymous function, for example
f = @(x,y)x.^2.*y.^2
In general for my problem I don't know how many arguments f will have. Nor do I know how many elements each argument will have.
I want to pass in a single element as an argument. If x and y are scalars, I can define z = num2cell(x,y), then write
f(z{:})
But if x and y are vectors this doesn't work. I could write
for ii=1:2; z = { x(ii);y(ii) }; f(z{:}) ;end
but of course I want to avoid the loop.
Is there some efficient way to obtain what I want by writing something like
f(q{:})
where q{:} is a cell array with each cell containing a vector rather than a scalar.
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Walter Roberson
Walter Roberson 2013-2-26
num2cell(x,y) is not the same thing as {x,y} when x and y are scalars. Instead num2cell(x,y) says to use y as the dimension number for the num2cell(x) operation.

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Walter Roberson
Walter Roberson 2013-2-26
It appears to me that what you want is arrayfun:
arrayfun(f, x, y)
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Leo Simon
Leo Simon 2013-2-26
Thanks Walter, this is really helpful. For the benefit of anybody else reading, I'm expanding on your answer, to deal with my problem in which the function f has a variablenumber of arguments.
In my case, f could be
f = @(x1,x2,x3)[ prod(x1*x2*x3);prod(x1*x2*x3)]
or
f = @(x1,x2,x3,x4)[prod(x1*x2*x3*x4);prod(x1*x2*x3*x4)];
where the xi's could be scalars or row vectors.
I want to be able to input a single argument that works for both.
The following works:
X = rand(4,3);
Z = {};for ii=1:size(X,2); Z = [ Z , X(:,ii) ] ; end
arrayfun(f,Z{:},'UniformOutput',false)
The third and fourth arguments appear to be needed because f is vector valued.

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