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Re: [Axiom-developer] severe (!) bug in normalize
From: |
Francois Maltey |
Subject: |
Re: [Axiom-developer] severe (!) bug in normalize |
Date: |
05 Dec 2006 22:16:23 +0100 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 |
Francois Maltey <address@hidden> writes:
And I let a error :
replace line 205
numexpo := numexpo -$MP cst1::Integer::R *$MP k::MP
cst := cst * (first argument k **$Rep cst1::Integer)
output([cst, numexpo::%]::OutputForm)$OutputPackage
The old one was :
cst := first argument k ** cst1::Integer
What do you want for Gosper algorithm in the famus quotient u(n)/u(n-1).
With or without exp ? with or without power ?
the expr.spad I send you don't suppose (a,b,c) in R+
So we don't have (a^b)^c = a^(bc)
But other simplifications are done where n is a real number, not a letter.
(a^u)^n = a^(nu)
exp (n ln a) = a^n, the fraction.
(exp a)^n exp b / exp c = exp (na+b-c)
(na)^u = n^u a^u
(a/n)^u = a^n / n^u
exp (n log a - log c) = a^n / c
I hope I let no error in mathematics formula :
1 / (z^u) = z^(-u) \neq (1/z)^u -- try with z=-1 and u=1/2
It seems that my expr.spad is right for the sum function :
sum ( q^n, n)
sum (n * q^n, n)
sum (n^2 * q^n, n)
sum (exp n, n)
sum ((n-1)*n^2 * q^n, n)
but have an error in :
sum (n * exp n, n)
sum (n^3 * q^n, n)
Even with print-spy I don't understand where is the mistake.
Hope this help you !
Francois