Updates:
Cc: ondrej.certik Vinzent.Steinberg Ronan.Lamy
Comment #2 on issue 1981 by asmeurer: lambert simplifications
http://code.google.com/p/sympy/issues/detail?id=1981
I'm fine with numerical evaluation, but not so sure about the first two.
Chris makes a good point that some symbolic things do need to happen, like
exp(log(x)). On the other hand, I am beginning to wonder even about that
one. In my work on integration, I see a lot of exp(log(something)), that
is reduced automatically in SymPy. For example, one way to integrate cos()
is to represent it as exp(-log(tan(x)**2 + 1)/2) (because the derivative of
cos() is not a polynomial in cos(), it is not possible to deal with it as a
monomial directly). Also, exp(log(x)/2) is a common example of a function
that appears to be transcendental but is really algebraic (because it ==
sqrt(x)). While I use dummy variables for everything in the algorithm, so
this won't be a direct problem for me, it shows me how you might sometimes
want things even like that.
Anyway, CC'ing others who might possibly have an opinion on this. This
automatic evaluation question comes up a lot it seems. I wonder if we need
to formulate an official policy on it.
--
You received this message because you are subscribed to the Google Groups
"sympy-issues" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sympy-issues?hl=en.
