Problem using solve...



-----maxima-bounces at math.utexas.edu wrote: -----

>The?solutions?to?equations?like?yours?involve?the?Lambert?W?function,
>which?Maxima?currently?does?not?use?for?solving?equations,?though?it?does
>support?its?numerical?evaluation?(function?lambert_w).?

The to_poly_solver makes some effort to solve equations using the Lambert W function.

 (%i4) load(to_poly_solver)$

 (%i14) %solve(x * exp(x)=y,x);
 (%o14) %union([x=lambert_w(y)])

 (%i15) %solve(x^2 * exp(x^2)=y,x);
 (%o15) %union([x=%e^(%i*%pi*%z101)*sqrt(lambert_w(y))])

 (%i16) %solve(exp(1/x)/x = y,x);
 (%o16) %union([x=%e^(-2*%i*%pi*%z107)/lambert_w(y)])

In general, Lambert solver is weak:

 (%i18) %solve(exp(1/x) = x*y,x);
 Unable to solve
 Unable to solve
 Unable to solve
 (%o18) %solve([%e^(1/x)=x*y],[x])

--Barton