Perhaps I've missed it, but what
branch of the Lambert-W-function does
lambert_w represent?
Apparently only this one selected branch
is available? I need the function in
the interval [-1/e, 0[, and I need
exactly the other real-valued branch than
the one computed by lambert_w. How
to get that?
Oliver
On Tue, May 20, 2008 at 01:11:24PM -0500, Barton Willis wrote:
> The function "lambert_w" is new to 5.15.0 (thanks due to Raymond and
> Stavros).
> The solve doesn't know about lambert_w. So far, lambert_w evaluates for
> doubles (but not big floats):
>
> (%i5) lambert_w(5.60);
> (%o5) 1.392014569377103
> (%i6) diff(lambert_w(x),x);
> (%o6) %e^(-lambert_w(x))/(lambert_w(x)+1)
> (%i9) taylor(lambert_w(x),x,0,4);
> (%o9) x-x^2+(3*x^3)/2-(8*x^4)/3+...
>
> Barton
>
--
Dr. Oliver Kullmann
Computer Science Department
Swansea University
Faraday Building, Singleton Park
Swansea SA2 8PP, UK
http://cs.swan.ac.uk/~csoliver/