From:
<jea...@uc...> - 2007-09-24 22:56:57
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On 23 Sep 2007, at 00:54, 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 > Please redo ! Once is apparently not sufficient .. Or at least check that your equality above is not right! Correct coefficients with you sequence of denominators are -5i/54 , 5i/54 , 2/9 , 2/9 ... if I'm not mistaken. But this has no importance : > 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 The link documents quite well that it is an upstream problem, and the guy who claims he had no problems doesn't know what he is talking about: he also gets 6 digit coefficients, and no pole multiplicity. (and by the way, he is also using "Octave 2.9.13 on Mac OS X") > Can any confirm they get the same result? Sure I But as said, this is an upstream problem, not fink's ! JF Mertens |