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Multiple anonymous functions combined

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Isktaine
Isktaine on 18 Mar 2013
Hi,
I am trying ultimately to be able to define a new anonymous function from two previously defined functions, and pass this into a function. Say, for simplicity, I define:
D=@(d) d^2
C=@(c) c^c
then I try to define:
E=@(d,c) D(d)*C(c)
then this works. I can put in values of d and c and get (d^2)*(c^c) as an output from E. I am trying to understand how MATLAB defines the new function E. If I delete functions D and C from the workspace, and continue to call E(1,2) etc then E will continue to produce results, so it's as if MATLAB has stored C and D inside E itself.
However, if I pass E into a new function and ask it to calculate E(1,2) inside there - I get an error. (Undefined function or method 'mtimes' for input arguments of type 'function_handle'). So it's as if MATLAB has now forgotten D and C, so they are not built into E.
Can someone explain what is happening here? I'm just trying to grasp how these functions are working.
Thanks!

  1 Comment

Matt J
Matt J on 18 Mar 2013
However, if I pass E into a new function and ask it to calculate E(1,2) inside there - I get an error. (Undefined function or method 'mtimes' for input arguments of type 'function_handle').
This is not enough information. We need to know not just what error message you are seeing, but what particular statement in your code produces it. Please copy/paste the complete error message, ideally from a small example that we can run/reproduce it with.

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Answers (2)

Azzi Abdelmalek
Azzi Abdelmalek on 18 Mar 2013
Edited: Azzi Abdelmalek on 18 Mar 2013
You should pass E through input argument of your function
Example
function y=yfcn(a,b,f)
y=f(a,b)+500
Then call your function
out=yfcn(2,3,E)

  2 Comments

Isktaine
Isktaine on 18 Mar 2013
I have. So for example:
function out=Newfunction(E,c,d)
E(c,d)
end
But running
Newfunction(E,1,2)
yields the error: Undefined function or method 'mtimes' for input arguments of type 'function_handle'). So even though E has been passed in it doesn't appear to know what it is made up of.
Azzi Abdelmalek
Azzi Abdelmalek on 18 Mar 2013
For me it's working.Also it should be
function out=Newfunction(E,c,d)
out=E(c,d)
end

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Sean de Wolski
Sean de Wolski on 18 Mar 2013
You can use the function functions() to figure out the workspace of a E. Here is an example, as for the error - I cannot reproduce it:
function examplefh
D=@(d) d^2;
C=@(c) c^c;
E=@(d,c) D(d)*C(c);
passedInto(E)
ef = functions(E)
ef.workspace{1}
function passedInto(E)
E(1,2)

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