Re: Re: How to obtain numberical value from an

*To*: mathgroup at smc.vnet.net*Subject*: [mg81029] Re: [mg80997] Re: How to obtain numberical value from an*From*: DrMajorBob <drmajorbob at bigfoot.com>*Date*: Sat, 8 Sep 2007 03:54:42 -0400 (EDT)*References*: <fbohh3$f5a$1@smc.vnet.net> <19345541.1189157227539.JavaMail.root@m35>*Reply-to*: drmajorbob at bigfoot.com

Mathematica uses inverse functions to Solve equations, for instance. Bobby On Fri, 07 Sep 2007 01:09:07 -0500, rob <josh2499 at hotmail.com> wrote: > This looks interesting but what is it useful for? It appears > one must already know the form of the inversefunction to > apply it. I feel sure I'm missing something; can someone > point me to an actual practical use of this inversefunction > concept? Thanks. > > > Bob Hanlon wrote: > >> f[x_] := x; >> >> f /: InverseFunction[f] = f; >> >> InverseFunction[f][f[x]] >> >> x >> >> f[InverseFunction[f][x]] >> >> x >> >> InverseFunction[f][0.5] >> >> 0.5 >> >> f[x_] := x^2; >> >> f /: InverseFunction[f] = Sqrt; >> >> InverseFunction[f][f[x]] >> >> Sqrt[x^2] >> >> f[InverseFunction[f][x]] >> >> x >> >> InverseFunction[f][4] >> >> 2 >> >> >> Bob Hanlon >> >> ---- Nasser Abbasi <nma at 12000.org> wrote: >> >>> Hello; >>> >>> Are inverse function in Mathematica only have symbolic form and can'= t = >>> be >>> used to evaluate numerically? >>> >>> Anything I am trying is not working, this is a very simple example: >>> >>> f[x_] := x >>> InverseFunction[f][x] >>> >>> Now, how to evaluate anything out of the above? say for x=0.5, I = >>> expected to >>> get .5, but all I get is just >>> f(^-1)[x][.5] >>> >>> any ideas? Very little help on InverseFunctions. >>> >>> Nasser >>> >>> >> >> >> > > -- = DrMajorBob at bigfoot.com