Dear Serge Steer, Thank you very much for your response. Your code works fine. However, I still have some problem with this pfss function. For example, I try to decompose a fractional polynomial that has multi-order poles. H(z) = 1 / { (1-s)^2 * (1+s) }
You can find following from my console: -->s = poly(0,'s'); -->h = 1 / ( (1 + s) * (1 - s)^2) h = 1 ------------- 2 3 1 - s - s + s -->pf = pfss(h, 1/%eps) pf = pf(1) - 9420237.9 ------------- - 1.0000000 + s pf(2) 9420237.6 --------- - 1 + s pf(3) 0.25 ---- 1 + s I also checked: -->pf(1)+pf(2) ans = 0.75 - 0.25s ------------ 2 1 - 2s + s I have no idea about this situation. Can you help me out! Thank you in advance! --Tin Nguyen -----Original Message----- From: users [mailto:users-boun...@lists.scilab.org] On Behalf Of Serge Steer Sent: Tuesday, October 14, 2014 6:36 PM To: users@lists.scilab.org Subject: Re: [Scilab-users] Problem with partial fraction decomposition (dfss) You just need to tune the rmax optionnal parameter pf = pfss(tf2ss(hz),5);length(pf) Serge Steer Le 13/10/2014 10:12, tinnguyen a écrit : > Hi guys, > I'm having trouble using scilab's function pfss to decompose a > polynomial in order to do inverse Z transform. Following is my code: > --> z = poly(0,'z') > --> hz = z^2 / (1 - 6*z + 11*z^2 - 6*z^3) pf = pfss(tf2ss(hz)) > --> length(pf) > The fourth command returns '1'. However, I believe it should be 3. I > also did the decomposition manually and got the result as: hz = > 0.5/(1-z) + -1 / > (1-2*z) + 0.5/(1-3*z). > Nevertheless, if I change the numerator of hz from z^2 to z or z^3, > pfss works correctly. I definitely have no idea!!!? :D Please take a > look and correct me if i'm wrong. > Thank you so much! > > > > > -- > View this message in context: > http://mailinglists.scilab.org/Problem-with-partial-fraction-decomposi > tion-dfss-tp4031331.html Sent from the Scilab users - Mailing Lists > Archives mailing list archive at Nabble.com. > _______________________________________________ > users mailing list > users@lists.scilab.org > http://lists.scilab.org/mailman/listinfo/users > _______________________________________________ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users _______________________________________________ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users