Made changes for better user-interpretation of series which are demonstrably divergent

[faze-geek]

References to other Issues or PRs

Closes #14191

Brief description of what is fixed or changed

Modified : concrete/summations.py
Modified : concrete/tests/test_sums_products.py
Added code for required series which are known to be divergent but on master it returns self .So a converge check is added once the summation fails ,which is useful information for the user.
Secondly anything constant should be treated as convergent .I observed that on master -

>>> Sum(cos(n), (n, x, x + 1)).doit()
cos(x) + cos(x + 1)
>>> Sum(cos(n), (n, x, x + 1)).is_convergent()
False

Here if 'x' was a number then on master the output is 'True'. The basic observation here was that cos(n) anyways will always stay bounded and hence cos(x) + cos(x+1) should be convergent.
After my commits -

>>> Sum(cos(x), (x, n, n + 10)).doit()
cos(n) + cos(n + 1) + cos(n + 2) + cos(n + 3) + cos(n + 4) + cos(n + 5) + cos(n + 6) + cos(n + 7) + cos(n + 8) + cos(n + 9) + cos(n + 10)
>>> Sum(cos(x), (x, n, n + 10)).is_convergent()
True 

This gives 'True' unless n is substituted S.Infinity/oo

Other comments

I will be adding appropriate tests and look into the failed checks soon !

Release Notes

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#### References to other Issues or PRs
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Closes #14191

#### Brief description of what is fixed or changed
Modified : ` concrete/summations.py `
Modified : ` concrete/tests/test_sums_products.py `
Added code for required series which are known to be divergent but on master it returns `self` .So a converge check is added once the summation fails ,which is useful information for the user.
Secondly anything constant should be treated as convergent .I observed that on master -
```
>>> Sum(cos(n), (n, x, x + 1)).doit()
cos(x) + cos(x + 1)
>>> Sum(cos(n), (n, x, x + 1)).is_convergent()
False
```
Here if  'x' was a number then on master the output is 'True'. The basic observation here was that cos(n) anyways will always stay bounded and hence cos(x) + cos(x+1) should be convergent.
After my commits -
```
>>> Sum(cos(x), (x, n, n + 10)).doit()
cos(n) + cos(n + 1) + cos(n + 2) + cos(n + 3) + cos(n + 4) + cos(n + 5) + cos(n + 6) + cos(n + 7) + cos(n + 8) + cos(n + 9) + cos(n + 10)
>>> Sum(cos(x), (x, n, n + 10)).is_convergent()
True 
```
This gives 'True' unless n is substituted `S.Infinity/oo`
#### Other comments
I will be adding appropriate tests and look into the failed checks soon !

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[anutosh491]

@faze-geek The tests are failing because of the another issue which has been fixed here #22200 by me . It's done from my side and needs review to merge , maybe @oscargus or @smichr can help us out with that ! I don't see your code is responsible for the error but yeah the changes you made would involve this to be done .

On master we have

>>> Sum(Piecewise((1/4*2**d, d>=-1), (0, True)), (d, -oo, -1)).is_convergent()
TypeError: Invalid NaN comparison

On my pr

>>> Sum(Piecewise((1/4*2**d, d>=-1), (0, True)), (d, -oo, -1)).is_convergent()
True

[faze-geek]

@faze-geek The tests are failing because of the another issue which has been fixed here #22200 by me . I don't see your code is responsible for the error but yeah the changes you made would involve this to be done .

Thanks for informing me about this . I looked into it and feel if it is a SymPy issue ,once #22200 is merged my failing checks will get resolved .