Matlab functions - summation

Hey,

I'm a beginner in Matlab.

I try at the moment to transfer a code which was written in Mathematica. There, I have many different functions w(k), e(k), f(k), etc. and another function X(w(k),e(k),f(k)). Let's say for simplicity that this function X(w(k),e(k),f(k)) does the following:

 X(w(k),e(k),f(k))=Sum(w(k),k)+Sum(e(k)*f(k))

I tried a simpler version of this as follows:

function [wk,ek,S] = myfun(U,n,J,a)
ek = 2*J*(1-cos(k*a));
wk = sqrt(e(k)*(e(k)+ 2*U*n));
S = Sum??
end

The problem now is that I cannot even calculate ek and wk because I have to give Matlab a value of k? Does anyone know a possible to implement this?

Answer 1

[Arnab Sen]

My understanding is that you would like to have some alternative for symbolic math in 'Mathematica' for function call.

From the code you have provided I notice that you try to store the reference of the function into a variable what in MATLAB is called 'function handle'. You can do this by creating 'anonymous function' and store their handle to the variable.

The following code illustrates this approach:

function [wk,ek,S] = myfun(U,n,J,a)
k=2;
ek = @(k)2*J*(1-cos(k*a));
ek(k);
wk = @(k)sqrt(ek(k)*(ek(k)+ 2*U*n));
wk(k)
S =@(k)ek(k)+wk(k);
S(k)
end

Now, you do not need to provide the value of 'k' to execute the function. For more details about 'anonymous function' and 'function handle' refer to the following links:

http://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

http://www.mathworks.com/help/matlab/matlab_prog/creating-a-function-handle.html