Question: How to avoid this error while Differentiation?

try_IG.mw

The following codes is a part of my program for computing ING at several points of r between -1 and 1 (by a step of for example 0.1 or even smaller for a better pointplot of ING(r) ):

H:=(r, teta) -> h(r, zn, teta) # h is a complicated function of (r, z, teta) (referred to the attached maple file) and   zn is a given number

F:= r -> int(H(r, teta), teta= 0…alpha)

IN:=r -> F(r)*conjugate(F(r))/N    # N is  a number evaluated before

ING:=r -> diff(IN(r), r);

If I want to evaluate ING at (for example) r = 0.2 as follows:

eval (ING(r), r = 0.2);

An error appeared:  Error, (in simpl/abs) abs is not differentiable at non-real arguments

How can I avoid this error?

I’ll be thankful if anyone could help me on this issue (by modifying my program)…

Thanks in Advance,

Sara