Opened 9 years ago

Closed 9 years ago

#485 closed bug (fixed)

some other strange thing with factorize

Reported by: gorzel Owned by: somebody
Priority: major Milestone: 3-2-0 and higher
Component: factory Version: 3-1-6
Keywords: Cc: hannes

Description

The following number field of degree 20 is an extension of degree 10 over Q(\sqrt{-3}).

If one stries to factorize x2+3 or x2-x+1 w.r.t. dp ordering, one gets the factors instantly:

>  ring r3mdp =(0,a),(x),dp;
>  minpoly =  a^20-a^19-8*a^18-15*a^17+42*a^16+132*a^15-222*a^14-270*a^13+1047*a^12
+956*a^11-2420*a^10-2656*a^9+2982*a^8+2049*a^7+3012*a^6+2721*a^5+747*a^4-294*a^3
+496*a^2-88*a+16;
> factorize(x2+3);
[1]:
   _[1]=1
   _[2]=x+(5811509098288175/306519909026147928a19-634996061741945/34057767669571992a18-23329891665988393/153259954513073964a17-87484580999531437/306519909026147928a16+60699176089318807/76629977256536982a15+192282842781606179/76629977256536982a14-643086131425631869/153259954513073964a13-791629020107704475/153259954513073964a12+6126182547255395821/306519909026147928a11+931426194768221773/51086651504357988a10-1768831789796499049/38314988628268491a9-1917282564708576274/38314988628268491a8+8808685906467116581/153259954513073964a7+11463945503690163763/306519909026147928a6+8184955772174168785/153259954513073964a5+17046065808513522955/306519909026147928a4+5409593761541114315/306519909026147928a3-126792704548225739/76629977256536982a2+421020323019636704/38314988628268491a-36307803956385688/38314988628268491)
   _[3]=x+(-5811509098288175/306519909026147928a19+634996061741945/34057767669571992a18+23329891665988393/153259954513073964a17+87484580999531437/306519909026147928a16-60699176089318807/76629977256536982a15-192282842781606179/76629977256536982a14+643086131425631869/153259954513073964a13+791629020107704475/153259954513073964a12-6126182547255395821/306519909026147928a11-931426194768221773/51086651504357988a10+1768831789796499049/38314988628268491a9+1917282564708576274/38314988628268491a8-8808685906467116581/153259954513073964a7-11463945503690163763/306519909026147928a6-8184955772174168785/153259954513073964a5-17046065808513522955/306519909026147928a4-5409593761541114315/306519909026147928a3+126792704548225739/76629977256536982a2-421020323019636704/38314988628268491a+36307803956385688/38314988628268491)
[2]:
   1,1,1

wHowveer with local ordering ds, a result will not obtained, but the memory consumption increaes rapidly.

> ring r3mds =(0,a),(x),ds;
>  minpoly =  a^20-a^19-8*a^18-15*a^17+42*a^16+132*a^15-222*a^14-270*a^13+1047*a^12   +956*a^11-2420*a^10-2656*a^9+2982*a^8+2049*a^7+3012*a^6+2721*a^5+747*a^4-294*a^3
+496*a^2-88*a+16;
> factorize(x2+3);

Remarks.:

1.) Although #482 was, by construction, related to this problem, the fix given there does not cure the char 0 case.

2.) This has been checked with ix86-Linux version 3-1-6 (3160) Apr 11 2013 06:01:55

the x86 version from nighly builds 11-4-2013 gives on Ubuntu

gorzelc@SCHAF12:/tmp/Singular/3-1-6/x86_64-Linux$ ./Singular 
Illegal instruction (core dumped)

Change History (1)

comment:1 Changed 9 years ago by hannes

Resolution: fixed
Status: newclosed

problem with pNorm for alg.extensions fixed.

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