How can I write the arguments of an anonymous function when programming?

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Piockñec 2014-4-17

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评论： per isakson 2014-4-18

采纳的回答： per isakson

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Good afternoon, my question arises when trying to programme the following code:

s(i+1)=NRK(Dt*f(tv(i+1),x)+s(i)-x,s(i));

Where NRK=NRK(function , numeric scalar) This was the symbolic implementation, with f=symbolic function, and x a symbolic array of unknowns.

The thing is that working with symbolic expressions can solve the issue, but this goes inside a loop, and symbolic tools slow down suprisingly the performance in a ratio of 100 times! However, anonymous functions do a perfect job.

My try was the following:

h=@([arguments (i.e. a, b, c, ...])Dt*f(t(i+1),[arguments (i.e. a, b, c,...])+s(i)-[a b c ...];
s(i+1)=NRK(@h,s(i));

How can I write these arguments? Is it possible? Thank you very much!

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Answer 1

per isakson 2014-4-17

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编辑：per isakson 2014-4-18

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Doesn't the info in Anonymous Functions cover your case?

I'm guessing. Try something like to create the anonymous function

    Dt = ???;
    s  = ???; 
    f  = ???;
    fh = @(a,b,c,ii) Dt*f( t(ii+1),a,b,c) + s(ii)-[a,b,c];

(What are Dt, s, f and t ?) And call it

fh(a,b,c,ii)

.

Added later: With varying number of input variables

Try

    [fh1,fh2] = cssm( );
    a   = 'a1';
    b   = 'b2';
    c   = 'c3';
    fh1( a )
    fh1( a, b, c )
    fh2( a )
    fh2( a,b,c )

which returns

    a1
    a1, b2, c3
    a1
    a1, b2, c3

where

    function    [fh1,fh2] = cssm( )
    fh1  = @(varargin) foo( varargin{:} ); 
    fh2  = @(varargin) disp( strjoin( varargin, ', ' ) );
        function    foo( varargin )
           disp( strjoin( varargin, ', ' ) )
        end
    end

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Answer 2

Piockñec 2014-4-18

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Thank you for your answer! Your solution is right, when writing an anonymous function for 3 variables (a,b,c). The problem is that the number of variables can vary (a,b,c,d,e,f...)... because x is a symbolic array of unkwnowns.

However, I have written the programme so that I do not need to solve my issue. Thank you again!!!