Re: Inverse Function
- To: mathgroup at smc.vnet.net
- Subject: [mg123619] Re: Inverse Function
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Tue, 13 Dec 2011 05:42:12 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
On 12/12/11 at 6:43 AM, harryhar800 at gmail.com (Harry Har) wrote: >I'm newbie in Mathematica. I want to find the inverse function of >y=(ax +b)/(cx+d). How to to this in Mathematica? Many thank's. In this particular case, Solve can be used to find the inverse function as follows: In[9]:= eq = y == (a x + b)/(c x + d); sol = Solve[eq, x]; And the desired function is: In[11]:= f = x /. First[sol] Out[11]= (d*y - b)/(a - c*y) Which can be verified to be the inverse function by: In[12]:= (f /. (Rule @@ eq)) // Simplify Out[12]= x However, this method is limited to functions which can be explicitly inverted symbolically something that cannot be done in general.