RE: solving non-algebraic exponential equations
- To: mathgroup at smc.vnet.net
- Subject: [mg38092] RE: [mg38059] solving non-algebraic exponential equations
- From: "David Park" <djmp at earthlink.net>
- Date: Tue, 3 Dec 2002 04:30:07 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Eva,
Instead of NDSolve you could try something like this...
f[a_, b_] := Exp[-Pi*a/x] + Exp[-Pi*b/x]
Plot[f[1.1,2.5]-1,{x,0,10}];
FindRoot[f[1.1, 2.5] == 1, {x, 6}]
{x -> 7.71189}
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
From: Eva Hohberger [mailto:eva.hoehberger at gmx.net]
To: mathgroup at smc.vnet.net
I am trying to solve the following equation for given values of two
parameters a and b:
NSolve[Exp[-Pi*a/x] + Exp[-Pi*b/x] == 1, x]
This is straightforward for integer values of the parameters a and b
(e.g. a=1, b=1). However, Mathematica is unable to compute the
solution for non-integer values of a and b (e.g. a=1.1, b=1.1; even
a=1.0, b=1.0 doesn't work). Instead, the error message "Solve::"tdep":
"The equations appear to involve the variables to be solved for in an
essentially non-algebraic way." is produced.
Can anybody point out a way to overcome this problem and to obtain a
solution?
Thanks,
Eva