Re: Re: InverseFunction[]
- To: mathgroup at smc.vnet.net
- Subject: [mg41971] Re: [mg41950] Re: InverseFunction[]
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Wed, 11 Jun 2003 13:18:15 -0400 (EDT)
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <bbt23g$nj3$1@smc.vnet.net> <bc1jh1$bjp$1@smc.vnet.net> <200306110749.DAA02507@smc.vnet.net>
- Reply-to: murray at math.umass.edu
- Sender: owner-wri-mathgroup at wolfram.com
What does "knows about" mean in your answer? Evidently Mathematica knows a NAME (ProductLog) for the inverse function and can evaluate it numerically. But what is the definition of the function as Mathematica knows it? Paul Abbott wrote: > In article <bc1jh1$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 > -- Reply to "REPLY TO" address and NOT to the "FROM" address!! Otherwise I will never see your reply!!!!!!!!!!!!!!!!!!!!!! Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305
- References:
- Re: InverseFunction[]
- From: Paul Abbott <paul@physics.uwa.edu.au>
- Re: InverseFunction[]