ellpointtoz() bug?

[Michael Somos <somos@grail.cba.csuohio.edu>]

Sorry about that last message about ellisoncurve. I actually was on the
trail of another bug with ellpointtoz().

                    GP/PARI CALCULATOR Version 2.0.17 (beta)
                i686 running linux (ix86 kernel) 32-bit version
              (readline v2.2 enabled, extended help not available)

                           Copyright (C) 1989-1999 by
          C. Batut, K. Belabas, D. Bernardi, H. Cohen and M. Olivier.

Type ? for help, \q to quit.
Type ?12 for how to get moral (and possibly technical) support.

   realprecision = 28 significant digits
   seriesprecision = 16 significant terms
   format = g0.28

parisize = 4000000, primelimit = 500000
gp> E=ellinit([0,0,1,-1,0]);
gp> for(n=-6,6,print(n" "ellpow(E,[0,0],n)" "ellpointtoz(E,ellpow(E,[0,0],n))))
-6 [6, -15] 0.4093610007515452132328238921 + 0.E-29*I
-5 [1/4, -3/8] 1.338953716036940887638023236 + 1.225694690993395030427112415*I
-4 [2, 2] 2.268546431322336562043222581 + 0.E-29*I
-3 [-1, 0] 0.2046805003757726066164119460 + 1.225694690993395030427112415*I
-2 [1, -1] 1.134273215661168281021611290 + 0.E-28*I
-1 [0, -1] 2.063865930946563955426810634 + 1.225694690993395030427112415*I
0 [0] 0
1 [0, 0] 2.063865930946563955426810634 + 1.225694690993395030427112415*I
2 [1, 0] 1.134273215661168281021611290 + 0.E-28*I
3 [-1, -1] 2.788778145856187023215598033 + 1.225694690993395030427112415*I
4 [2, -3] 0.7249122149096230677887873983 + 0.E-29*I
5 [1/4, -5/8] 1.654504930195018742193986742 + 1.225694690993395030427112415*I
6 [6, 14] 2.584097645480414416599186087 + 0.E-29*I


This gives a different answer on 1.39 which seems correct to me.

            GP/PARI CALCULATOR Version 1.39
                     (hppa version)

Copyright 1989-1994 by C. Batut, D. Bernardi, H. Cohen and M. Olivier

Type ? for help

\precision      = 28
\serieslength   = 16
\format         = g0.28
\prompt         = ? 
stacksize = 4000000, prime limit = 500000, buffersize = 30000
? E=initell([0,0,1,-1,0]);
? for(n=-6,6,print(n," ",powell(E,[0,0],n)," ",zell(E,powell(E,[0,0],n))))
-6 [6, -15] 0.4093610007515452132328238921 - 6.310887241736054420000000000 E-30*i
-5 [1/4, -3/8] 1.338953716036940887638023236 + 1.225694690993395030427112415*i
-4 [2, 2] 2.268546431322336562043222581 +  0.E-29*i
-3 [-1, 0] 0.2046805003757726066164119460 + 1.225694690993395030427112415*i
-2 [1, -1] 1.134273215661168281021611290 +  0.E-28*i
-1 [0, -1] 2.063865930946563955426810634 + 1.225694690993395030427112415*i
0 [0] 0
1 [0, 0] 0.9295927152853956744051993445 + 1.225694690993395030427112415*i
2 [1, 0] 1.859185430570791348810398689 +  0.E-28*i
3 [-1, -1] 2.788778145856187023215598033 + 1.225694690993395030427112415*i
4 [2, -3] 0.7249122149096230677887873983 +  0.E-29*i
5 [1/4, -5/8] 1.654504930195018742193986742 + 1.225694690993395030427112415*i
6 [6, 14] 2.584097645480414416599186087 + 6.310887241736054420000000000 E-30*i


The current answer seems wrong for some n. Shalom, Michael