function handle with input parameters
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I need to invoke the 'eigs' function to calculate the lowest eigenvalue of a hermitian matrix, which I do not construct explicitly. I thus use a function handle to realize the action of the matrix on a vector. My code is like this
[evector, evalue]=eigs(@fun_Htimesx, dim, 1,'smallestreal');
In the function 'fun_Htimesx', I have
function y = fun_Htimesx(x)
global H transx_many transy_many qx qy Lx Ly
That is, the hermitian matirx 'H' and many other parameters are set as global variables so that I do not need to pass them to the function handle.
Now, my question is, how can avoid global variables? How to pass parameters to a function handle?
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Accepted Answer
Star Strider
on 1 May 2024
I am not certain that I understand what you want to do.
One approach:
function y = fun_Htimesx(x, H , transx_many, transy_many, qx, qy, Lx, Ly)
If you only want to pass ‘x’ to it (for example in an optimisation function call), the function handle becomes:
@(x)fun_Htimesx(x, H , transx_many, transy_many, qx, qy, Lx, Ly)
providing that all the other argumnents are already present in the calling script (or function script) workspace. Otherwise, just pass ‘x’ to it if that is the only argument that changes. The others will be passed automatically, providing they are preseent in the calling script (or function script) workspace.
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2 Comments
Star Strider
on 1 May 2024
If you want to use all of them to calculate ‘y’ use this approach:
y = fun_Htimesx(x, H , transx_many, transy_many, qx, qy, Lx, Ly);
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