Karim BELABAS on Tue, 26 Nov 2002 16:28:56 +0100 (MET) |
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Re: polynomial arithmetic feature? |
On Fri, 22 Nov 2002, Michael Somos wrote: > Forgot to mention that : > > ? ( (x+y+1)*z*(x+y)/y ) / ( z*(x+y)/y ) > %1 = x + (y + 1) > ? \v > GP/PARI CALCULATOR Version 2.2.4 (development CHANGES-1.491) > i686 running linux (ix86 kernel) 32-bit version > (readline v4.2a enabled, extended help not available) > > So it seems to be that something changed since then. Probably a > typo or attempt to fix one thing breaking another. Shalom, Michael It did not work in 2.2.4 either, but it was well hidden: (16:15) gp > (x+y+1)*z*(x+y)/y %1 = z/y*x^2 + ((2*z*y + z)/y)*x + (z*y + z) (16:15) gp > z*(x+y)/y %2 = z/y*x + z (16:15) gp > %1 / %2 %3 = z/z*x + (y + 1) If the intermediate results of %1 and %2 are not simplified (as in your direct computation), then the result was correct. In 2.2.5, in order to fix a "missed simplification" problem, I added calls to simplify() when simplifying a rational function, applied to numerator and denominator. Thus exhibiting the bug. The bug was actually in content( t_RFRAC ), which apparently made the simplifying assumption that numerator and denominator were polynomials in the same variable (or scalars) ==> content(y/x) = 1 Should be all right in CVS now. Karim. -- Karim Belabas Tel: (+33) (0)1 69 15 57 48 Dép. de Mathématiques, Bât. 425 Fax: (+33) (0)1 69 15 60 19 Université Paris-Sud Email: Karim.Belabas@math.u-psud.fr F-91405 Orsay (France) http://www.math.u-psud.fr/~belabas/ -- PARI/GP Home Page: http://www.parigp-home.de/