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Re: Inverse function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg99378] Re: Inverse function
  • From: dh <dh at metrohm.com>
  • Date: Mon, 4 May 2009 06:01:13 -0400 (EDT)
  • References: <gth5gc$evb$1@smc.vnet.net>


Hi,

InverseFunction is only a symbolic inverse. To get the inverse of a 

function you may use e.g. Solve or in more complicated cases Reduce. 

Your example:

sol=Solve[y == 5/(2 - x), x]

You may write this as a function by e.g.:

fun = Evaluate[x /. sol[[1]] /. y -> #] &

with this:

f[1] evaluates to -3



Daniel





davef wrote:

> I have two questions: 

> 

> 1. Is it possible to find the inveses function for one-to-one function in Mathematica 7? 

> 

> For example the inverse of 5/(2-x) is 2-(5/x). I have tried Inverse and InverseFunction but I cannot produce the inverse function. 

> 

> Can anyone explain how to get Mathematica to produce this result? (See attached output screenshot.) 

> 

> 

> 2. Is it possible to change the format of the output for a recprical? 

> 

> For example, instead of writing the output of Inverse[5/(2-x)] as (5/(2-x))^-1, can the output be set to produce (2-x)/5?

> 




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