Re: Reduce/Solve

*To*: mathgroup at smc.vnet.net*Subject*: [mg49916] Re: [mg49912] Reduce/Solve*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Fri, 6 Aug 2004 03:09:32 -0400 (EDT)*References*: <200408051322.JAA05969@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 5 Aug 2004, at 15:22, Dr A.H. Harker wrote: > > Dear All, > I tend to think of Reduce as a more powerful tool than Solve, > yet with > > eq = J == J0 (1 + r/d) Exp[-r/d] > ss = Solve[eq, r] > tt = Reduce[eq, r] > > I get useful output from Solve, but Reduce returns the expression > unevaluated. What am I missing? Mathematica 5.0.0.0 under Windows XP. > > Tony > > Dr A.H. Harker > Director of Postgraduate Studies > Deputy Head, Condensed Matter and Materials Physics Group > Department of Physics and Astronomy > University College London > Gower Street > LONDON > WC1E 6BT > (44)(0)207 679 3404 > a.harker at ucl.ac.uk > > > > Reduce is not "more power full than Solve". If this were true what need would there be for Solve? Reduce attempts to give a complete solution and when that is impossible it returns no answer. In your particular case Solve produces a warning about using Inverse functions and tells you that you may not have a complete solution. That tells you exactly the reason why Reduce returns the original expression back to you. Andrzej Kozlowski Chiba, Japan http://www.mimuw.edu.pl/~akoz/

**References**:**Reduce/Solve***From:*"Dr A.H. Harker" <a.harker@ucl.ac.uk>