Solve

*To*: mathgroup at smc.vnet.net*Subject*: [mg57886] Solve*From*: R T <chromaticspace at yahoo.com>*Date*: Sat, 11 Jun 2005 03:35:44 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

I'm generating 9th degree polynomials with Mathematica from real world data. Then I'm using them in an application I'm writing in Xcode. This works beautifully! I get an equation like... -0.13249751088801668 + 0.06632187456026009*r^1 +0.06629492661634432*r^2 - 0.00005387198125569*r^3 -0.00002692675947693*r^4 + 0.00000001324872853*r^5 +0.00000000435988550*r^6 - 0.00000000000037184*r^7 -0.00000000000043768*r^8 + 0.00000000000000172*r^9 ...and in a function I wrote in Xcode, I supply r, say r = 5, and the answer 1.83303 is generated . BUT I need to start with the answer and solve for r. In Mathematica... answer = Solve[ -0.13249751088801668 + 0.06632187456026009*r^1 +0.06629492661634432*r^2 - 0.00005387198125569*r^3 -0.00002692675947693*r^4 + 0.00000001324872853*r^5 +0.00000000435988550*r^6 - 0.00000000000037184*r^7 -0.00000000000043768*r^8 + 0.00000000000000172*r^9 == 1.83303, r] ...solves to... {r -> -61.9036 - 40.911 I}, {r -> -61.9036 + 40.911 I}, {r -> -59.8256}, {r-> -6.}, {r -> 5}, {r -> 73.5579}, {r -> 82.3158 - 32.3924 I}, {r -> 82.3158 + 32.3924 I}, {r -> 200.908}} and knowing from the origional real world data that r is in a range between 0 and 16 .... the solution is {r -> 5}. _________________________________________________________________ Mathmatically how does the "Solve" function do this? My application needs to dynamically "Solve" the equation, so I need to write something in "C". Any leads greatly appreciated. Thanks, Rick T. __________________________________ Discover Yahoo! Get on-the-go sports scores, stock quotes, news and more. Check it out! http://discover.yahoo.com/mobile.html

**Follow-Ups**:**Re: Solve***From:*Andrzej Kozlowski <andrzej@akikoz.net>