Re: [Maxima-discuss] probable bug in sqrt

[Michel T. <ta...@lp...>]

In fact i still think there is a bug somewhere. Seeing there is a 
"linsolve" involved, and remembering that there is a problem in linsolve 
related to gcd computations, because it uses a complicated algorithm to 
avoid producing unnecessary huge denominators, i have tried to change 
the gcd algorithm to  other values and i found that the computation then 
crashes - so there is indeed a bug in linsolve in this particular case.

With the same program given by Igor in his first message, adding 
gcd:subres before linsolve i get:


(%i3) unksAT:[cA[5],cA[4],cA[3],cA[2],cA[1]]$

(%i4) gcd:subres$

(%i5) soAT:linsolve(eqsAT, unksAT);
CQUOTIENT: quotient is not exact
  -- an error. To debug this try: debugmode(true);

Commenting out domain:complex doesn't help. The message CQUOTIENT: 
quotient is not exact is produced in rat3a.lisp, and means that the 
remainder of an euclidean division does not vanish when it should. By 
the way, the subresultant algorithm for computing gcds is supposed to be 
absolutely sure if  slower than the standard one.

Le 11/11/2025 à 14:53, Richard Fateman a écrit :
> The earlier bug reports describe the situation in detail.  It is not that
> there is a bug in sqrt, but a complication resulting from how programs 
> deal with algebraic dependencies.

-- 
Michel Talon