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Re: InverseFunction[]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg41950] Re: InverseFunction[]
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Wed, 11 Jun 2003 03:49:47 -0400 (EDT)
  • Organization: The University of Western Australia
  • References: <bbt23g$nj3$1@smc.vnet.net> <bc1jh1$bjp$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <bc1jh1$bjp$1 at smc.vnet.net>,
 wself at msubillings.edu (Will Self) wrote:

> You can easily write down a function which has an inverse, but the
> inverse cannot be expressed in closed form, or in symbols that anyone
> has invented.  For example, f[x_]= x*E^x.  This function is increasing
> on (for example) the interval [1,3], therefore an inverse exists, at
> least for 1 <= x <= 3.  But (as far as I know) this inverse function
> has no name.

Your point is valid. However, try Solve[x*E^x == y, x] and you'll see 
Mathematica knows about the inverse function for your example.

Cheers,
Paul

-- 
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