Re: Re: Simplifying with positive constants
- To: mathgroup at smc.vnet.net
- Subject: [mg26109] Re: Re: [mg26062] Simplifying with positive constants
- From: Fernando Suarez Ornani <djago at usa.net>
- Date: Tue, 28 Nov 2000 01:55:56 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Is your Mathematica Version 3? I get: In[8]:= Simplify[1/2(r*a - a*d - Sqrt[4*r*a^2*d + (-r*a + a*d)^2]), a > 0 && r > 0 && d > 0] Simplify::nonopt : Options expected (instead of (a > 0 && r > 0 && d > 0) beyond position 1 in Simplify[(1/2)(-a d + a r - Sqrt[4 a^2 d r + (a d - a r)^2],<<1>>]. An option must be a rule or a list of rules. Out[8]:= Simplify[1/2(r*a - a*d - Sqrt[4*r*a^2*d + (-r*a + a*d)^2]), a > 0 && r > 0 && d > 0] instead of what you get. Got any clue? Seems mi version doesn't like this kind of options after simplify... >You just need to specify some assumptions for Simplify or FullSimplify to >use: > >In[10]:= >Simplify[1/2(r*a - a*d - Sqrt[4*r*a2*d + (-r*a + a*d)2]), > a > 0 && r > 0 && d > 0] >Out[10]= >-a d > >-matt > > > > > >djago at my-deja.com <mailto:djago at my-deja.com> on 11/21/2000 11:55:51 PM > >To: mathgroup at smc.vnet.net <mailto:mathgroup at smc.vnet.net> >cc: >Subject: [mg26109] [mg26062] Simplifying with positive constants > > > >I'm trying to calculate some results and when I evaluate them I get: >1/2(r*a-a*d-Sqrt[4*r*a2*d+(-r*a+a*d)2] > >I know that this is a complicated way of saying: >r*a > >but Mathematica (3.0) doesn't seems to get the idea... > >I've tried with FullSimplify and so on... but Mathematica won't let a >go out of the Sqrt function. Maybe If I could tell Mathematica that a, >r and d are real and positive values... > >Can somebody give me a hint of how to do this??? > >Thx!