On Apr 23, 1:22 am, Kelvin Li <ltwis...@gmail.com> wrote: > On Apr 14, 1:09 pm, Kelvin Li <ltwis...@gmail.com> wrote: > > > > > On Apr 14, 1:03 am, Burcin Erocal <bur...@erocal.org> wrote: > > > > Hi Kelvin, > > > > On Tue, 12 Apr 2011 10:43:25 -0700 (PDT) > > > > Kelvin Li <ltwis...@gmail.com> wrote: > > > > Is anybody working on implementing something similar to mathematica's > > > > InverseFunction? Or is there already a trac ticket out there? If there > > > > is interest and it is not on trac, I can open a ticket. > > > > > Here is the link to mma's docs on InverseFunction: > > > > >http://reference.wolfram.com/mathematica/ref/InverseFunction.html > > > > > The question of finding the inverse to a given callable symbolic > > > > function has popped up a few times. In the cases that I have seen, it > > > > seems that Sage does not have this sort of feature. Here is one > > > > instance from AskSage: > > > > >http://ask.sagemath.org/question/502/can-sage-compute-the-inverse-of-... > > > > > Anybody know what is being done (or has been done)? > > > > I don't think anybody is working on this. Feel free to open a ticket > > > and give the link to the MMA documentation in the description. A full > > > solution to this would probably require adding an attribute to all > > > symbolic functions to point to their inverses. > > > This is now #11202 (http://trac.sagemath.org/sage_trac/ticket/11202). > > > > Are you interested in working on this? I could try to explain how to go > > > about this in more detail if there is interest. > > > Thanks Burcin, I will give it a shot. I have never hacked Sage before > > (or any large software project, for that matter), so expect lots of > > mistakes from me. :-) > > > Is there something I should be aware of before I dive into the > > symbolics code? I am imagining adding an `inverse` method to the > > symbolic functions classes, wherever that may be. In the end, I also > > imagine being able to find the inverses of vector functions (but both > > input and output must have the same number of dimensions). > > > Would it be okay to call Sage's `solve` function to find the inverse, > > or would there be problems with that? > > > > Cheers, > > > Burcin > > This thread has been dormant for a while, but I thought it would be > worth mentioning that I found a way to find the inverse of symbolic > expressions in one variable, using the "roots" method. See my latest > answer at: > > http://ask.sagemath.org/question/502/can-sage-compute-the-inverse-of-... > > Even with this, I would like to find inverses of vector functions > (i.e. more than one variable). Not sure if this is possible yet with > the same approach of using "roots". The relevant Trac ticket is #11202 > (http://trac.sagemath.org/sage_trac/ticket/11202). > > Ideas? Comments? > > -- Kelvin
A quick look at the code for the "roots" method shows that it simply calls Maxima's "solve". Therefore, finding the inverse of vector functions should be relatively easy to implement, using the same approach. Updating Trac ticket #11202 again... -- 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
