Range can be accepted in Sum

[czgdp1807]

References to other Issues or PRs

Fixes #16806

Brief description of what is fixed or changed

Read the discussion at the above Issue and see the diff.

Other comments

N/A

Release Notes

• concrete
  • Range can be passed as limit to Sum

[sympy-bot]

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• concrete
  • Range can be passed as limit to Sum (#16810 by @czgdp1807 and @smichr)

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<!-- Your title above should be a short description of what
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#### References to other Issues or PRs
<!-- If this pull request fixes an issue, write "Fixes #NNNN" in that exact
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Fixes https://github.com/sympy/sympy/issues/16806

#### Brief description of what is fixed or changed
Read the discussion at the above Issue and see the diff.

#### Other comments
N/A

#### Release Notes

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<!-- BEGIN RELEASE NOTES -->
* concrete
  * `Range` can be passed as limit to `Sum`
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Update

The release notes on the wiki have been updated.

[czgdp1807]

@smichr I have tried to fix it, can you please take a look and tell me whether it is merge-able.

[codecov]

Codecov Report

Merging #16810 into master will increase coverage by <.001%.
The diff coverage is 90%.

@@              Coverage Diff              @@
##            master    #16810       +/-   ##
=============================================
+ Coverage   73.844%   73.844%   +<.001%     
=============================================
  Files          619       619               
  Lines       159617    159635       +18     
  Branches     37463     37468        +5     
=============================================
+ Hits        117868    117882       +14     
  Misses       36289     36289               
- Partials      5460      5464        +4

[smichr]

Looks good. One mod that can be made in future prs is to remove the sympify of the Tuple V flatten result since all Tuple args are Basic.

[smichr]

Let's make this canonical, however, by using lo=inf hi=sup and d=abs of step. Range(9,0,-2) should give same symbolic sum of i before doit as that of Range(1,10,2).

[czgdp1807]

Thank you @smichr for making the commits. :-)

[smichr]

Hmm. That code is a little contorted. It should now work if you pass an Idx with Range. I'm not sure what should happen if lo and hi are not given with Idx, however, so am raising an error.

[czgdp1807]

Sure, we can add a TODO task for that case in the code.

[smichr]

One more time...

[smichr]

Do you have any popcorn? ;-)

[czgdp1807]

Up for a movie then? 😉

[czgdp1807]

@smichr Tests passed. Is there anything else to change?

[smichr]

No, LOL!