Thanks! In the meantime, any suggestions for a work-around (besides write the entire program in PARI or C)?
Eliot On Feb 18, 3:26 am, Dan Drake <dr...@kaist.edu> wrote: > On Wed, 17 Feb 2010 at 10:25PM -0800, eliot brenner wrote: > > I have a program that includes the command to evaluate the K-Bessel > > function using Pari: it will sometimes be called with arguments like > > the following: > > > bessel_K(5*i,320,"pari",100) > > > which evaluates the Bessel function at index (first variable) 5i, > > value (second variable) 320, with 100 precision. > > > This exhibits some unexpected behavior when called from within SAGE, > > as follows. The bessel_K fucntion, with fixed index, and growing > > second variable exhibits exhibits exponential decay, as shown by these > > (correct) calculations performed in Pari itself: > > [...] > > ? besselk(5*I,200) > > > %25 = 1.1515969255360280546036312473791321981 E-88 + > > 1.7485172637427202649 E-133*I > [...] > > sage: bessel_K(5*i,200,"pari",100) > > > -4.3246147682420463563103557554e40 + > > 4.3246147682420463567825924037e40*I > > > So they agree until the second variable reaches at least 50, but then > > SAGE starts reporting wrong answers. > > Yikes. That's awful. > > There are some other ways in which that function is broken; > seehttp://trac.sagemath.org/sage_trac/ticket/3426. > > I'll mention these problems on that ticket, so that when we fix it, we > put in some doctests to make sure this doesn't happen again. > > Dan > > -- > --- Dan Drake > ----- http://mathsci.kaist.ac.kr/~drake > ------- > > signature.asc > < 1KViewDownload -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
