use assumptions for integration variables

[smichr]

References to other Issues or PRs

fixes #7334

Brief description of what is fixed or changed

definite integration limits are used to assign assumptions for the integration variables when they differ from the integration variable.

Other comments

The more strict assumption (e.g. positive when limits are nonnegative) is used since whether 0 is contained at a limit or not will not matter. (see @asmeurer comment on linked issue) Since positive and not extended_positive is used, this will also imply that the variable is finite and, again, the result of the integral should not depend on the inclusion of +/-oo.

Release Notes

• integrals
  • assumptions based upon definite integration limits are automatically applied to integration variables

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• integrals
  • assumptions based upon definite integration limits are automatically applied to integration variables (#17093 by @smichr)

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#### References to other Issues or PRs
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fixes #7334

#### Brief description of what is fixed or changed

definite integration limits are used to assign assumptions for the integration variables when they differ from the integration variable.

#### Other comments

The more strict assumption (e.g. positive when limits are nonnegative) is used since whether 0 is contained at a limit or not will not matter. (see @asmeurer comment on linked issue) Since `positive` and not `extended_positive` is used, this will also imply that the variable is finite and, again, the result of the integral should not depend on the inclusion of +/-oo.

#### Release Notes

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- integrals
    - assumptions based upon definite integration limits are automatically applied to integration variables
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Update

The release notes on the wiki have been updated.

[smichr]

@oscargus , I had made the previous PR online and couldn't update remotely. Here is the same PR with the wester test modified to remove assumptions. Still, reversing the limits makes a big difference on the time it takes to do the integral...that is a different issue, I think.

[oscargus]

I do think it solves #16014 as well. Just trying the added code manually it seems like it does. The issue was really that the assumptions should not have to be done manually and since you could remove them in the test, it means that it solves it. Time for order is another thing, which indeed is a problem as such, but not really what the issue was about.

(I've been thinking about a fix for this recently, but I do not think that the code would have been as simple and clean as your...)

[codecov]

Codecov Report

Merging #17093 into master will increase coverage by 12.916%.
The diff coverage is 90.909%.

@@              Coverage Diff              @@
##           master    #17093        +/-   ##
=============================================
+ Coverage   61.56%   74.476%   +12.916%     
=============================================
  Files         623       623                
  Lines      161197    161219        +22     
  Branches    37838     37848        +10     
=============================================
+ Hits        99234    120071     +20837     
+ Misses      56270     35815     -20455     
+ Partials     5693      5333       -360