Bill Allombert on Sat, 29 Jan 2005 12:44:24 +0100 |
[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]
Re: Pari/GP 2-2-9.exe bug report |
On Thu, Jan 27, 2005 at 01:34:54PM -0500, John Nicol wrote: > Hi there, > > I noticed the following behavior(s) which seem buggy to me. This is Pari-GP 2-2-9.exe. I am running Windows XP Professional with 1GB of memory. > > #1: Factoring above and beyond 2^122 seems to encounter problems. > (10:18) gp > factor(2^122 -1) > *** factor: tempfile /tmp/FREL.400.3056 already exists. Factoring large integers use the MPQS code that rely on temporary files to store data. does the file '/tmp/FREL.400.3056' exists on your system? > #2: contfrac(sqrt(x)) and contfrac(sqrt(x),n) terminate earlier than I would expect from definition. Rounding error? > This is a quadratic surd, with infinitely many terms and period 2. Here I'm expecting arbitrarily many terms, but I only get 31. > > (10:30) gp > contfrac(sqrt(15)) > %22 = [3, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 7] > (10:30) gp > contfrac(sqrt(15),,300) > %23 = [3, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 7] This is not a bug: sqrt(15) is a 28 decimal approximation of the square root of 15, but is also a 28 decimal approximation of lots of other real numbers. contfrac() will return only terms that are common to all those numbers. Cheers, Bill.