[Maxima-bugs] [maxima:bugs] #4814 Default GCD algorithm can't handle algebraic

[Raymond T. <rt...@us...>]

This should probably be documented in the manual?    Although you've already fixed this, maybe it should have just signaled an error if spmod can't handle it instead?   Magically changing the gcd algorithm for this case mkes it difficult to know what happened if you have spmod but some other algorithm was actually used.  

Note:  I didn't look at the changes you actually made.


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**[bugs:#4814] Default GCD algorithm can't handle algebraic**

**Status:** closed
**Group:** None
**Labels:** gcd algebraic 
**Created:** Sun Jul 12, 2026 11:56 AM UTC by David Scherfgen
**Last Updated:** Sun Jul 12, 2026 12:42 PM UTC
**Owner:** nobody


>From the manual:

> To take the gcd when an algebraic is present, e.g., `gcd (x^2 - 2*sqrt(2)* x + 2, x - sqrt(2))`, the option variable `algebraic` must be `true` and `gcd` must not be `ez`.

This example doesn't work with the default `gcd` value of `spmod`:

~~~
(%i1) gcd (x^2 - 2*sqrt(2)* x + 2, x - sqrt(2)), algebraic;
(%o1)                             x - sqrt(2)
~~~

We should probably automatically select a different algorithm when algebraics are present.


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