Hi Richard, On Fri, Dec 5, 2014 at 4:48 PM, Richard Fateman <fate...@gmail.com> wrote: > You are heading into erroneous waters. > It doesn't matter that 3>0. sqrt(9) has two values, +3 and -3. > Just because some other systems make this mistake does not mean > sympy should do this. > > If you want to say something about the choice of branch for sqrt(x^2), > you have to say something about sqrt(x^2), not x. > > It may be sensible if you mean to restrict the square root function. > But not that way. > Good luck
Do you know any computer algebra system that treats functions as multivalued, i.e. sqrt(9) returns both +3 and -3? I would like to play with it. Incidentally, I've spent lot of time lately thinking about how complex functions can be implemented in a CAS, see e.g. these threads: https://github.com/sympy/sympy/issues/8502 https://groups.google.com/forum/#!topic/sage-devel/6j-LcC6tpkE/discussion Essentially there are two consistent ways --- either treat functions as multivalued or as singlevalued (on a principal branch). Ondrej -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CADDwiVDVLVn1HjJTipQzMh3a5Ud2RyQcQMczg5LE_X4X-1S3VQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
