AW: Emergent Help: NSolve Problems!

*To*: mathgroup at smc.vnet.net*Subject*: [mg39823] AW: [mg39753] Emergent Help: NSolve Problems!*From*: Matthias.Bode at oppenheim.de*Date*: Sat, 8 Mar 2003 02:48:05 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hello Chengzhou, Version 4.1.1: Input: s^10 + 10 s^9 + 10 s^8 + 10 s^7 + 10 s^6 + 10 s^5 + 10 s^4 + 1 /. s -> -8.999981180131652 Output: -4.76837158203125*^-7 Acceptably close to zero? Best regards, Matthias Bode Sal. Oppenheim jr. & Cie. KGaA Koenigsberger Strasse 29 D-60487 Frankfurt am Main GERMANY Tel.: +49(0)69 71 34 53 80 Mobile: +49(0)172 6 74 95 77 Fax: +49(0)69 71 34 95 380 E-mail: matthias.bode at oppenheim.de Internet: http://www.oppenheim.de -----UrsprÃ¼ngliche Nachricht----- Von: Chengzhou Wang [mailto:wcz at ece.ucsd.edu] Gesendet: Donnerstag, 6. MÃ¤rz 2003 08:35 An: mathgroup at smc.vnet.net Betreff: [mg39753] Emergent Help: NSolve Problems! Hi, guys I have some complicated polynomials, and I want to calculate its roots. HOwever, when I use NSolve, it creates some problems. Say a simple example: temp[s_]=s^10+10 s^9+ 10 s^8 +10 s^7 +10 s^6+ 10 s^5 +10 s^4 +1; NSolve[temp[s]==0, s] It will give: Out[4]= {{s -> -8.99998}, {s -> -1.06539}, {s -> -0.468828 - 0.886239 I}, > {s -> -0.468828 + 0.886239 I}, {s -> -0.409684 - 0.469948 I}, > {s -> -0.409684 + 0.469948 I}, {s -> 0.401048 - 0.312597 I}, > {s -> 0.401048 + 0.312597 I}, {s -> 0.51015 - 0.878693 I}, > {s -> 0.51015 + 0.878693 I}} But when I plug in the first number, which is "-8.99998", it should give a value close to zero. However, it gives: In[5]:= temp[-8.99998] Out[5]= -411.473 The other roots seems OK. Does anyone know why? This is just a simple example. I have some more complicated polynomials to deal with. Thanks in advance! PS: Please reply (cc) to my email. I did not subscribe my email to the this email group! -- Chengzhou