Re: How to obtain numberical value from an

*To*: mathgroup at smc.vnet.net*Subject*: [mg80997] Re: How to obtain numberical value from an*From*: rob <josh2499 at hotmail.com>*Date*: Fri, 7 Sep 2007 02:09:07 -0400 (EDT)*References*: <fbohh3$f5a$1@smc.vnet.net>

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 >> >> > > >