On Apr 23, 10:44 am, Benjamin Jones <benjaminfjo...@gmail.com> wrote: > The `symbolic_inverse` function you posted on ask.sagemath looks good. > I might suggest catching the RuntimeError when no roots are found and > raising a more informative error, e.g. "Sage could not find a symbolic > inverse" ...
I am thinking about directly using "solve()", rather than "roots()", to implement "inverse()". That way I can raise my own exception. Another consideration is whether we want to let "inverse()" itself be representable as a symbolic expression. I need to learn about how this works in Sage, but I am referring to the behavior of "integral()" when it can't integrate something. For example: sage: Ei(x).integral(x) integrate(Ei(x), x) sage: Ei(x).integral(x).diff(x) Ei(x) In the case of "inverse()", this might look like: sage: f(x) = x + sin(x) sage: f.inverse(x) inverse(x + sin(x), x) sage: f(f.inverse(x)) x + sin(x) Then this can be used to allow Sage to apply the inverse function theorem[1], for example. I have a lot to learn about how symbolics works in Sage before I can work on this. Maybe the easier route would be not to let inverse() be representable as a symbolic expression and simply raise an exception if Maxima's "solve()" fails. Later down the line, I might be able to do something fancier. I would like to know whether letting inverse() "play" with the symbolics as outlined above is desirable. [1] http://en.wikipedia.org/wiki/Inverse_function_theorem -- Kelvin -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
