Re: Solve / NSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg95396] Re: Solve / NSolve*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Sat, 17 Jan 2009 05:31:16 -0500 (EST)

On 1/16/09 at 6:09 AM, sigmundv at gmail.com (SigmundV) wrote: >Thanks to Andrzej and Jean-Marc for the discussion on the >differences between Solve and NSolve. Have any of you tried to run >the code i provided (including the missing function definition which >I provided later)? I'm aware that Solve and NSolve do not use the >same algorithm to solve an equation, but it does not seem "logical" >to me that they don't give the same solution to the same system of >algebraic equations. What could be the reason for this? For any problem where you are using machine precision numbers, there will always be values that lead to different solutions when different algorithms are used. This comes about due to rounding and precision issues. This is inherent with anything other than exact arithmetic. This issue is not limited to just Solve/NSolve nor is it a Mathematica issue.