maxima-bugs

[Maxima-bugs] [maxima:bugs] #4630 expand not idempotent (orderlessp?)

[Stavros M. <mac...@us...>]

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**[bugs:#4630] expand not idempotent (orderlessp?)**

**Status:** open
**Group:** None
**Labels:** Lisp Core - Simplification expand orderlessp 
**Created:** Tue Nov 04, 2025 07:57 PM UTC by Stavros Macrakis
**Last Updated:** Tue Nov 04, 2025 07:57 PM UTC
**Owner:** nobody


<pre>
vv: ((1/sqrt(2)-2^(1/3))/2^(1/3)-%i/2^(5/6))*(-(%i/2^(5/6))-(2^(1/3)+1/sqrt(2))/2^(1/3))$
expand(vv) =>
2^(1/6)*%i+1/2^(5/6)-1/2^(2/3)-1/2^(5/6)+1
expand(%) =>
2^(1/6)*%i-1/2^(2/3)+1
</pre>



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[Maxima-bugs] [maxima:bugs] #4630 expand not idempotent (orderlessp?)

[Stavros M. <mac...@us...>]

- Description has changed:

Diff:

~~~~

--- old
+++ new
@@ -5,3 +5,5 @@
 expand(%) =>
 2^(1/6)*%i-1/2^(2/3)+1
 </pre>
+
+Maxima 5.48.1 SBCL 2.5.7 MacOS 15.7.1 Intel

~~~~




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**[bugs:#4630] expand not idempotent (orderlessp?)**

**Status:** open
**Group:** None
**Labels:** Lisp Core - Simplification expand orderlessp 
**Created:** Tue Nov 04, 2025 07:57 PM UTC by Stavros Macrakis
**Last Updated:** Tue Nov 04, 2025 07:57 PM UTC
**Owner:** nobody


<pre>
vv: ((1/sqrt(2)-2^(1/3))/2^(1/3)-%i/2^(5/6))*(-(%i/2^(5/6))-(2^(1/3)+1/sqrt(2))/2^(1/3))$
expand(vv) =>
2^(1/6)*%i+1/2^(5/6)-1/2^(2/3)-1/2^(5/6)+1
expand(%) =>
2^(1/6)*%i-1/2^(2/3)+1
</pre>

Maxima 5.48.1 SBCL 2.5.7 MacOS 15.7.1 Intel



---

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[Maxima-bugs] [maxima:bugs] #4630 expand not idempotent (orderlessp?)

[Barton W. <wil...@us...>]

This is an ancient bug in  `simplus`, not in orderlessp. The code in `altsimp` fixes this bug:

~~~
(%i3) load("altsimp")$

(%i4) vv: ((1/sqrt(2)-2^(1/3))/2^(1/3)-%i/2^(5/6))*(-(%i/2^(5/6))-(2^(1/3)+1/sqrt(2))/2^(1/3))$

(%i5) expand(vv);

(%o5) 2^(1/6)*%i-1/2^(2/3)+1
(%i6) expand(vv);

(%o6) 2^(1/6)*%i-1/2^(2/3)+1
~~~

The fix in `altsimp` is in the `do-over` scheme--see the explanation starting at line 329 in share/contrib/altsimp/altsimp.lisp.   

Last I tried,l the Maxima testsuite does not trigger the `do-over` scheme.


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**[bugs:#4630] expand not idempotent (orderlessp?)**

**Status:** open
**Group:** None
**Labels:** Lisp Core - Simplification expand orderlessp 
**Created:** Tue Nov 04, 2025 07:57 PM UTC by Stavros Macrakis
**Last Updated:** Tue Nov 04, 2025 07:58 PM UTC
**Owner:** nobody


<pre>
vv: ((1/sqrt(2)-2^(1/3))/2^(1/3)-%i/2^(5/6))*(-(%i/2^(5/6))-(2^(1/3)+1/sqrt(2))/2^(1/3))$
expand(vv) =>
2^(1/6)*%i+1/2^(5/6)-1/2^(2/3)-1/2^(5/6)+1
expand(%) =>
2^(1/6)*%i-1/2^(2/3)+1
</pre>

Maxima 5.48.1 SBCL 2.5.7 MacOS 15.7.1 Intel



---

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[Maxima-bugs] [maxima:bugs] Re: #4630 expand not idempotent (orderlessp?)

[Stavros M. <mac...@us...>]

Thanks for the quick reply! I see that **contrib/altsimp** has very different code for **simplus** than **src/simp** does. Has it been promoted to the default **simplus** now? Or are there known problems with it? Or are we afraid that there are unknown problems with it?


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**[bugs:#4630] expand not idempotent (orderlessp?)**

**Status:** open
**Group:** None
**Labels:** Lisp Core - Simplification expand orderlessp 
**Created:** Tue Nov 04, 2025 07:57 PM UTC by Stavros Macrakis
**Last Updated:** Tue Nov 04, 2025 09:32 PM UTC
**Owner:** nobody


<pre>
vv: ((1/sqrt(2)-2^(1/3))/2^(1/3)-%i/2^(5/6))*(-(%i/2^(5/6))-(2^(1/3)+1/sqrt(2))/2^(1/3))$
expand(vv) =>
2^(1/6)*%i+1/2^(5/6)-1/2^(2/3)-1/2^(5/6)+1
expand(%) =>
2^(1/6)*%i-1/2^(2/3)+1
</pre>

Maxima 5.48.1 SBCL 2.5.7 MacOS 15.7.1 Intel



---

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[Maxima-bugs] [maxima:bugs] #4630 expand not idempotent (simplus)

[Stavros M. <mac...@us...>]

- **labels**: Lisp Core - Simplification, expand, orderlessp --> Lisp Core - Simplification, simplus
- **summary**: expand not idempotent (orderlessp?) --> expand not idempotent (simplus)



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**[bugs:#4630] expand not idempotent (simplus)**

**Status:** open
**Group:** None
**Labels:** Lisp Core - Simplification simplus 
**Created:** Tue Nov 04, 2025 07:57 PM UTC by Stavros Macrakis
**Last Updated:** Tue Nov 04, 2025 09:50 PM UTC
**Owner:** nobody


<pre>
vv: ((1/sqrt(2)-2^(1/3))/2^(1/3)-%i/2^(5/6))*(-(%i/2^(5/6))-(2^(1/3)+1/sqrt(2))/2^(1/3))$
expand(vv) =>
2^(1/6)*%i+1/2^(5/6)-1/2^(2/3)-1/2^(5/6)+1
expand(%) =>
2^(1/6)*%i-1/2^(2/3)+1
</pre>

Maxima 5.48.1 SBCL 2.5.7 MacOS 15.7.1 Intel



---

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[Maxima-bugs] [maxima:bugs] #4630 expand not idempotent (simplus)

[Barton W. <wil...@us...>]

Correction:  This fix isn't in the `do-over` scheme, but it has something to do with  handling of rational powers of integers (in the function `surd-convert`).   Maybe the culprit is in `simpexpt` but the `altsimp` code works around the bug.

Also, running the testsuite triggers the `do-over` scheme about seven times. 


---

**[bugs:#4630] expand not idempotent (simplus)**

**Status:** open
**Group:** None
**Labels:** Lisp Core - Simplification simplus 
**Created:** Tue Nov 04, 2025 07:57 PM UTC by Stavros Macrakis
**Last Updated:** Tue Nov 04, 2025 09:50 PM UTC
**Owner:** nobody


<pre>
vv: ((1/sqrt(2)-2^(1/3))/2^(1/3)-%i/2^(5/6))*(-(%i/2^(5/6))-(2^(1/3)+1/sqrt(2))/2^(1/3))$
expand(vv) =>
2^(1/6)*%i+1/2^(5/6)-1/2^(2/3)-1/2^(5/6)+1
expand(%) =>
2^(1/6)*%i-1/2^(2/3)+1
</pre>

Maxima 5.48.1 SBCL 2.5.7 MacOS 15.7.1 Intel



---

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