After a day spent trying to implement a workaround for a special case of this issue:
http://trac.sagemath.org/sage_trac/ticket/6480 I thought it would be a good time to review the status of some of the earlier issues with how we represent ordinary (partial) derivatives. Most relevant is this old thread: http://groups.google.com/group/sage-devel/browse_thread/thread/6074f9d1b04b39f8/ which highlights the lack of a practical inverse for the D[] notation. For instance, in sage: sage: a=diff(f,x,x)+diff(f,x)/x sage: str(a) 'D[0](f)(x, y)/x + D[0, 0](f)(x, y)' but as far as I could find by reading the trac, groups, asksage and google, there is no way to _enter_ a differential expression from such a str() output. That capability would be important in, for example, a javascript JSON structure for communicating an O(P)DE, or for input from function generators in other languages, or anyplace where its inconvenient to generate a correct diff() python/sage expression. If I missed such a facility, my apologies, but if not, has there been any progress on any of these issues? (Also, I wasn't very successful in finding good JSON equation formats via google or stackoverflow, and I'd really like to know if there are any symbolic O(P)DE formats for javascript.) John Hoebing -- 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
