On Fri, Dec 23, 2011 at 8:08 PM, gsagrawal <[email protected]> wrote:
> * > * > Try k=Add(x,x,evaluate=False) > print k # prints x+x > print -k # prints -2*x > > As in __neg__ function it do Add(*args) again. > > > It seems somewhere sympy is limited in evaluate=False part. > I think we should have one property IsEvaluated in expr class. > So all the functions (like __neg__) can use that while forming the > expression again . > > > Yes, this is a known issue and there has been some discussion in http://groups.google.com/group/sympy/browse_thread/thread/56015fa6bad18051/358687f02c0bb8d3?lnk=gst&q=Hold#358687f02c0bb8d3 about implementing a Hold function. cse, btw, uses a temporary class Sub to represent a subtraction which it then locates again later to "undo" what it did in the preprocessing step. ( btw, I am using the most current version of sympy. ) -- You received this message because you are subscribed to the Google Groups "sympy" 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?hl=en.
