Numerical solution to a simple exponential equation
Subject: Numerical solution to a simple exponential equation
From: David Holmgren
Date: Tue, 3 Jul 2001 16:42:24 -0600
Hi,
There is a Newton method program in the share subdirectory; this should
help, I hope
Dave Holmgren
Dr. David E. Holmgren,
Imaging Scientitst,
SMART Technologies, Inc.
Calgary, AB, Canada
http://www.smarttech.com
[403]-235-1452, ext. 251
DavidHolmgren@smarttech.com
> -----Original Message-----
> From: Virgil [SMTP:virgilinux at yahoo]
> Sent: Tuesday, July 03, 2001 3:56 PM
> To: maxima@www.ma.utexas.edu
> Subject: [Maxima] Numerical solution to a simple exponential equation
>
> I am interested in obtaining solutions to equations involving exp(x),
> that is %E^x.
>
> For a very simple example, consider:
>
> (C1) h(x):=x*exp(-x);
> (C2) solve(h(x)=1/4);
> x
> %E
> (D2) [x = ---]
> 4
>
> Of course, Maxima is correct to say that x=exp(x)/4 "solves" the above
> equation, but that is not really what one is looking for.
>
> Numerically, one can verify that x=0.36 and x= 2.15 would make
> h(x)=0.25.
>
> But, how to get Maxima to give this answer??
>
> I tried different "switches" for "solve" but could not find anyone that
> would lead to a numerical solution.
>
> I also found and tried the function zsolve, whose description sounds
> promising, but could not get it to work.
> Unfortunately, this function appears to be undocumented.
>
> Thanks in advance for any suggestions!
>
> __Virgil
>
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