Fixed issue with simplifying oo + imaginary

[oscargus]

References to other Issues or PRs

Closes #22020

Brief description of what is fixed or changed

Simplifying expressions of the type oo + I/2 used to throw an error. Not anymore.

Other comments

To be honest, I do not fully understand the logic behind the code I added, but it seems to work and avoids the int(c) that was the cause of all evil here.

Release Notes

• simplify
  • Fixed issue with simplifying infinity plus rational imaginary.

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• simplify
  • Fixed issue with simplifying infinity plus rational imaginary. (#22024 by @oscargus)

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Closes #22020

#### Brief description of what is fixed or changed
Simplifying expressions of the type `oo + I/2` used to throw an error. Not anymore.

#### Other comments
To be honest, I do not fully understand the logic behind the code I added, but it seems to work and avoids the `int(c)` that was the cause of all evil here.

#### Release Notes

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* simplify
     * Fixed issue with simplifying infinity plus rational imaginary.
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[jksuom]

The condition should probably be something like c.is_Number as int(c) is not implemented for finite complex numbers:

In [23]: I.is_infinite                                                          
Out[23]: False

In [24]: int(I)                                                                 
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)

TypeError: can't convert complex to int

In [25]: I.is_Number                                                            
Out[25]: False

[oscargus]

Ahh, I only noted the oo error, but that clearly makes sense. (For some reason the code doesn't come here for e.g. oo + I, only for oo+I/2 etc, and apparently not for many other cases with complex numbers...)

[oscargus]

However, as oo is a Number, I am not sure exactly what it should be. Right now it works and it seems like c rarely (if ever) an imaginary/complex number.

Also, c should by sympified as far as I can tell, so not obvious what the purpose of c == int(c) is? Check that c is an integer or something else? Maybe is_Integer is enough?

[oscargus]

I tried is_Integer only and so far so good. Pushing to run the complete test set.

[smichr]

Also, c should by sympified as far as I can tell, so not obvious what the purpose of c == int(c) is

Yes, c was generated from as_coeff_Mul so it will be sympified. Even I am not sure why the int was used.