Differentiation with symbolic function giving NaN value upon repeatedly executing

I am manually finding the residues at the poles of a complex function but when I execute this code in a for loop, or copy and paste it as I have done below, it works once and then just starts to output NaN. I know the code below is an unorganised approach, I had split it up this way only to debug.

I have tried to fix this for hours and have made no progress.

Any help would be greatly appreciated!!

syms Z
F = @(Z) ((exp(Z^2))/((Z-2)*(Z-3)))

sum_of_res = 0
current_pt = sings(1) %sings is the array of singular pts/poles

% using formula for residues
res1_fn = ((1/factorial(0))*diff(((Z-current_pt)^1)*F(Z), Z))
%replace 1 by m

Z = current_pt
c = subs(res1_fn) %this is done because res1_fn has to be evaluated at the pole (current_pt) after diff
sum_of_res = sum_of_res + c
disp(res1_fn) 
% substituting z0 in the res function



% finding residues at singularity number 2
current_pt = sings(2)
Z = current_pt
% using formula for residues
res2_fn = ((1/factorial(0))*diff(((Z-current_pt)^1)*F(Z), sym('Z')))
%replace 1 by m

Z = current_pt
c = subs(res2_fn)
sum_of_res = sum_of_res + c
disp(res2_fn)
% substituting z0 in the res function

[Torsten]

It would be interesting to know what F is.

[Aditya B]

Just added that bit to the top of the code block

Answer 1

[Torsten]

And why don't you simply evaluate

exp(z^2)/(z-3) at z=2 to get the residual at z=2 and

exp(z^2)/(z-2) at z=3 to get the residual at z=3 ?

[Aditya B]

I wanted to automate the entire process so that a general function could be made. If that proves to not be possible, I will have to go for this approach.

Thank you!