patch6

[Karim Belabas <karim@mpim-bonn.mpg.de>]

Yet another patch. Again a bug report by Gerhard (msg 13):

> (20:27) gp > idealnorm(nf,x)
> %34 = 133
> (20:28) gp > idealnorm(nf,Mod(x,nf.pol))
>   ***   incorrect type in gabs.

  That turns out to be an inocuous bug in nfbasistoalg(). When fed a
t_POLMOD, it would convert it to a higher (meaningless) polmod instead of
just copying it back. I added an extra consistency check as well.

Karim.

============================ patch 6 (2.0.alpha) ===========================

*** src/basemath/base3.c.orig	Fri Nov 14 04:53:17 1997
--- src/basemath/base3.c	Thu Nov 20 20:42:59 1997
***************
*** 446,451 ****
--- 446,463 ----
    avma=av; return v;
  }
  
+ /* polegal without comparing variables */
+ long
+ polegal_spec(GEN x, GEN y)
+ {
+   long i = lgef(x);
+ 
+   if (i != lgef(y)) return 0;
+   for (i--; i > 1; i--)
+     if (!gegal((GEN)x[i],(GEN)y[i])) return 0;
+   return 1;
+ }
+ 
  GEN
  basistoalg(GEN nf, GEN x)
  {
***************
*** 472,477 ****
--- 484,493 ----
        for (i=1; i<lx; i++) z[i]=(long)basistoalg(nf,(GEN)x[i]);
        return z;
  
+     case t_POLMOD:
+       if (!polegal_spec((GEN)nf[1],(GEN)x[1]))
+ 	err(talker,"not the same number field in basistoalg");
+       return gcopy(x);
      default: z=cgetg(3,t_POLMOD); z[1]=lcopy((GEN)nf[1]);
        z[2]=lmul(x,polun[varn(nf[1])]); return z;
    }
***************
*** 499,516 ****
    return z;
  }
  
- /* polegal without comparing variables */
- long
- polegal_spec(GEN x, GEN y)
- {
-   long i = lgef(x);
- 
-   if (i != lgef(y)) return 0;
-   for (i--; i > 1; i--)
-     if (!gegal((GEN)x[i],(GEN)y[i])) return 0;
-   return 1;
- }
- 
  GEN
  algtobasis(GEN nf, GEN x)
  {
--- 515,520 ----
--
Karim Belabas                          e-mail:
Max-Planck-Institut fuer Mathematik       karim@mpim-bonn.mpg.de
Gottfried-Claren-Str. 26               tel:
53225 Bonn (Germany)                      (00 49 228) 402-245