Re: Erf[InverseErf] -- making a function and its inverse cancel
- To: mathgroup at smc.vnet.net
- Subject: [mg69015] Re: Erf[InverseErf] -- making a function and its inverse cancel
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Sat, 26 Aug 2006 04:40:05 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <ecoq4t$35n$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
mktippett at gmail.com wrote: > How can I get an expression like Erf[InverseErf[0,1/3]] to simplify to > 1/3? > > Cos[ArcCos[1/3]] gives 1/3. Is there some assumption that I'm missing? > > thanks, > Mike > For reason of efficiency, Mathematica does not call systematically the simplification rules. You must nudge Mathematica to force the simplification. In[1]:= FullSimplify[Erf[InverseErf[0, 1/3]]] Out[1]= 1 - 3 In[2]:= N[Erf[InverseErf[0, 1/3]]] Out[2]= 0.333333 HTH, Jean-Marc