Re: Re: Confusing results with N[expr]?

*To*: mathgroup at smc.vnet.net*Subject*: [mg62356] Re: [mg62327] Re: Confusing results with N[expr]?*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Tue, 22 Nov 2005 04:41:58 -0500 (EST)*References*: <dlp320$1bs$1@smc.vnet.net> <200511210854.DAA22039@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 21 Nov 2005, at 17:54, Peter Pein wrote: > 2.) > Unprotect[Power]; > Power /: N[(x_)^(y_)] := Pow$[N[x], N[y]]; > Protect[Power]; > $Post = #1 /. Pow$ -> Power & ; > Well, I would not recommend it. As often happens if you change one of the basic arithmetic functions, there is be a price to pay if you do this. Here is an example: In[1]:= Unprotect[Power]; Power /: N[(x_)^(y_)] := Pow$[N[x], N[y]]; Protect[Power]; $Post = #1 /. Pow$ -> Power & ; In[5]:= Solve[N[x^2 - 1 == 0], x] "Inverse functions are being used by so some solutions may not be \ found; use Reduce for complete solution information. Out[5]= {} Solving polynomial equations has suddenly become harder (although, of course, if you do not use N things will still work fine). Andrzej Kozlowski

**References**:**Re: Confusing results with N[expr]?***From:*Peter Pein <petsie@dordos.net>