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[Axiom-developer] possible bug

 From: Martin Rubey Subject: [Axiom-developer] possible bug Date: 29 Apr 2008 18:00:25 +0200 User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4

```I'd be very grateful if somebody could look at the input file below. (Don't be
afraid, most of the definitions are not needed)

I would have thought that bug() would yield twice the same thing.  It may be a
mistake on my side, of course, but note that

* axiom does not compute

map(c +-> sqrtrule c, series(first Phi Psi Phi [x,y,Z.2], t=0)::ULS(EXPR INT,
t, 0))

* neither axiom nor fricas can compute

map(c +-> sqrtrule c, series(first Phi Psi Phi [x,y,Z.2], t=0)::ULS(EXPR INT,
t, 0))-first Phi Psi Phi [x,y,Z2]

since this is actual work, I'd be extremely grateful for help!

Martin

-------------------------------------------------------------------------------
K := ((t*y+t*x)*z*z+(t*y*y+(-x*y)+t*x*x)*z+t*x*y*y+t*x*x*y)
Z := zerosOf(K, z)

sqrtrule := rule sqrt(a^2*?b) == a*sqrt b
Z1 := map(c +-> sqrtrule c, series(Z.1, t=0)::ULS(EXPR INT, t, 0))::ULS(FRAC
POLY INT, t, 0)
Z2 := map(c +-> sqrtrule c, series(Z.2, t=0)::ULS(EXPR INT, t, 0))::ULS(FRAC
POLY INT, t, 0)

Phi l == [l.2 * l.3/ l.1, l.2, l.3]

Psi l == [l.1, l.1 * l.3/l.2, l.3]

-- I guess the following is a bug:
-- I cannot even subtract the two!
bug() ==
output map(c +-> sqrtrule c, series(first Phi Psi Phi [x,y,Z.2],
t=0)::ULS(EXPR INT, t, 0))
output first Phi Psi Phi [x,y,Z2]

```