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• algebras
  • Added hamilton's operators in Quaternion class in quaternion.py. (#22713 by @mayankray2020 and @praneethratna)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.11.

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#### References to other Issues or PRs
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#### Brief description of what is fixed or changed
This is a partial fix for #20769 and also part of this PR is taken from unmerged PR #20853 and made changes in code and tests as requested by @danilobellini

#### Other comments


#### Release Notes

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  * Added a new solver for logarithmic equations.

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* algebras
   * Added hamilton's operators in Quaternion class in quaternion.py.
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

ping @oscarbenjamin

Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)

Significantly changed benchmark results (master vs previous release)

       before           after         ratio
     [907895ac]       [d7bddf4f]
-         248±3ms          155±9ms     0.62  large_exprs.TimeLargeExpressionOperations.time_subs
-         264±5μs          133±8μs     0.50  matrices.TimeMatrixExpression.time_MatMul
-      17.2±0.7ms       9.66±0.7ms     0.56  matrices.TimeMatrixExpression.time_MatMul_doit
-      4.89±0.01s         394±30ms     0.08  polygon.PolygonArbitraryPoint.time_bench01
+      4.29±0.1ms       6.85±0.6ms     1.60  solve.TimeMatrixOperations.time_det(4, 2)
+      4.02±0.1ms       6.67±0.1ms     1.66  solve.TimeMatrixOperations.time_det_bareiss(4, 2)
+        45.6±2ms         81.0±4ms     1.78  solve.TimeMatrixSolvePyDySlow.time_linsolve(1)
+        46.4±3ms         82.5±6ms     1.78  solve.TimeMatrixSolvePyDySlow.time_solve(1)

Full benchmark results can be found as artifacts in GitHub Actions
(click on checks at the top of the PR).

CC @danilobellini

• Add Quaternion.versor() as a new name to Quaternion.normalize()

Sorry but I'm ain't understanding this , should a new method named versor be added in quaternion class or a line like versor = normalize should be added in the code ? but where can i include the documentation of versor method?

• Add Hamilton operators to the Quaternion documentation
• Add the deprecated terminology "norm" and "tensor" to the documentation

I feel these documentation changes be made in a separate PR after this is merged or maybe done with PR itself?

ping @danilobellini

I feel these documentation changes be made in a separate PR after this is merged or maybe done with PR itself?

Don't worry with those 3 other tasks, I was just stating the scope of these changes in order to avoid closing all the tasks from the original issue once this gets merged.

ping @danilobellini , I've made the changes as you have mentioned above, is this PR now good to be merged once all the tests are passing?

I edited the OP to say that this is a partial fix so that the issue is not closed when this is merged.

Thanks @praneethratna and @mayankray2020 and also @danilobellini for this work. I'll merge this now.

It would be good to update the original issue to say what is left to be done.