function handle with input parameters

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?

Answer 1

[Star Strider]

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.

.

[min lee]

@(x)fun_Htimesx(x, H , transx_many, transy_many,  qx, qy, Lx, Ly)

I got an error message 'too many input arguments'.

All other arguments like 'H' are parameters defining the hermitian matrix, which do exist in my script workspace. That is why I set them as global.

[Star Strider]

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);

.