Michael Somos on Wed, 8 May 2002 14:32:34 -0400 (EDT) |
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Re: GP: algdep() bug? |
Okay, I missed the obvious again. The degree of the polynomial should have been 32. It would have been 16 if complex integer coefficients were allowed. My mistake. Thanks for the info. I will try to remember in future. Shalom, Michael On Wed, 8 May 2002, Bill Allombert wrote: > On Sun, May 05, 2002 at 10:49:04PM -0400, Michael Somos wrote: > > Pari Developers, > > > > I don't know if this is exactly a bug, but perhaps there is some > > other explanation why it won't find the polynomial : > > > > ? p=x^8+1+9424*(-x^7+x^5+x^3-x)+7740*(x^6+x^2)+15494*x^4; > > ? p2=subst(p,x,I*x^2); > > ? rp2=polroots(p2); > > ? r2_7=rp2[7]; > > ? print(algdep(r2_7,16)); > > *** precision too low in lindep. > > > > It seems to me that 4000 digits should be enough, but I have been > > wrong before. Shalom, Michael > > This means that there is no relations of degree less than 32, so > algdep(r2_7,16) can't find anything. Increasing the precision make things > "worse" since it reduce the chance that algdep find a false relation. > (with \p9 you find x^5 - 1) >