Ben Abbott wrote: > I have both PPC and Intel installations of Octave. They both give the wrong > answer to this short script. > > num = [1 0 1]; > den = [1 0 18 0 81]; > [a,p,k,e] = residue(num,den) > > I did the math ... > > (x^2+1)/(x^4+18*x^2+81) = (2/9)/(x-3i) + (2/9)/(x+3i) + (1/54i)/(x-3i)^2 - > (1/54i)/(x+3i)^2 > > Thus, > > a = [1/54i 2/9 -1/54i 2/9] > p = [3i 3i -3i -3i] > k = [] > e = [2 1 2 1] > > However, my Intel version gives > > a = > > -3.0108e+06 - 1.9734e+06i > -3.0108e+06 + 1.9734e+06i > 3.0108e+06 + 1.9734e+06i > 3.0108e+06 - 1.9734e+06i > > p = > > -0.0000 + 3.0000i > -0.0000 - 3.0000i > 0.0000 + 3.0000i > 0.0000 - 3.0000i > > k = [](0x0) > e = > > 1 > 1 > 1 > 1 > > and my PPC version gives > > a = > > 8.4492e+06 - 3.9658e+06i > 8.4492e+06 + 3.9658e+06i > -8.4492e+06 + 3.9658e+06i > -8.4492e+06 - 3.9658e+06i > > p = > > 0.0000 + 3.0000i > 0.0000 - 3.0000i > -0.0000 + 3.0000i > -0.0000 - 3.0000i > > k = [](0x0) > e = > > 1 > 1 > 1 > 1 > > For reference, Matlab gives > > a = > > 0 - 0.0926i > 0.2222 - 0.0000i > 0 + 0.0926i > 0.2222 + 0.0000i > > > p = > > 0.0000 + 3.0000i > 0.0000 + 3.0000i > 0.0000 - 3.0000i > 0.0000 - 3.0000i > > k = > > [] > > A non-Fink installation for 2.9.14 produces the correct answer as well, see > the link below. > > http://www.nabble.com/bug-in-residue.m-tf4475396.html > > Can any confirm they get the same result? > > p.s. I tried posting to the users list, but forgot to subscribe before doing > that. I'll try to delete that post from Nabble momentarily. > I get the same thing as your PowerPC results on my own G4, for both a Fink and non-Fink installation of Octave 2.9.13 (from octave.sf.net) ; so that inclines me to think it's an upstream issue, and potentially solveable by updating the package to 2.9.14. (Maintainer cced)
For that matter, using 2.9.9 on Linux (Intel) I get: a = 7.4540e+03 - 9.9176e+06i 7.4540e+03 + 9.9176e+06i -7.4540e+03 + 9.9176e+06i -7.4540e+03 - 9.9176e+06i p = 0.0000 + 3.0000i 0.0000 - 3.0000i -0.0000 + 3.0000i -0.0000 - 3.0000i And with 2.9.13 on another Linux box: a = 7.4540e+03 - 9.9176e+06i 7.4540e+03 + 9.9176e+06i -7.4540e+03 + 9.9176e+06i -7.4540e+03 - 9.9176e+06i p = 0.0000 + 3.0000i 0.0000 - 3.0000i -0.0000 + 3.0000i -0.0000 - 3.0000i ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Fink-beginners mailing list Fink-beginners@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/fink-beginners
