Assigning a returned wave from a function without looping

Hello there,

I made a simple function that returns a sub-wave of the input wave. Reason for making it a function is to loop it over multiple 2D images and not create a mess in the experiment. Here is how it looks in use:

​Make/N=(75, 35)/O test2d
test2d = CreateSubwave2D_func(imageWave, 9.4, 10, 4, 5)[p][q]
// The function simply returns a sub-wave of the input 2D wave with x-range from 9.4 to 10 and y-range for 4 to 5.

The problem is that during assignment to "test2d", the function is invoked for every pair of p and q, running the function 75*35=2625 times just to create one sub-wave (I think this is what's happening). Is there a way to assign the whole returning wave to "test2d" without looping?

Another issue demonstrated in the snippet above is that I have to create a wave with predetermined dimensions to assign the returning wave to. Is there a way to create a flexibly-dimensioned wave that adheres to the returning wave? Something like this:

Make/N=(10, 10) test2d
test2d = CreateSubWave2D_func(imageWave, 9.4, 10, 4, 5) 
// the function returns a 75x35 wave. During assignment, test2d re-dimensions to match the returning wave's dimensions.

I can bypass all of this by using a macro instead, but as stated earlier it tends to create a lot of residue waves in the experiment which I have to kill manually, not being ideal for dealing with lots of data. An advice would be appreciated, thank you and happy Friday!