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Re: Simple question about inverse of a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg122529] Re: Simple question about inverse of a function
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Mon, 31 Oct 2011 06:50:24 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201110300922.EAA15359@smc.vnet.net>
  • Reply-to: drmajorbob at yahoo.com

f[t_] := (1 - t)^theta

Assuming[t >= 0 && t <= 1 && theta >= 1 &&
   theta < Infinity, {Quiet@InverseFunction[f][t]}]

{1 - t^(1/theta)}

Bobby

On Sun, 30 Oct 2011 04:22:58 -0500, Mikael  
<mikaen.anderson.1969 at gmail.com> wrote:

> I have a simple question on how to calculate the inverse of a a  
> function. This is the function I define:
>
> f[t_] := (1 - t)^theta
>
> To calculate the inverse I write:
>
> Assuming[t >= 0 && t <= 1 && theta >= 1 && theta < Infinity, {  
> InverseFunction[f[t]]}]
>
> but the answer I get is
>
> {InverseFunction[(1 - t)^theta]}.
>
> Now I know I can do this:
>
> In[11]:= Solve[f[g[x]]==x,g[x]]
> Out[11]= {{g[x]->1-x^(1/theta)}}
>
> but I wonder what is the correct way of specifying assumptions on t and  
> theta to make the InverseFunction work. Thanks.
>


-- 
DrMajorBob at yahoo.com



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