See also the idea at http://code.google.com/p/sympy/issues/detail?id=2738.
Aaron Meurer On Fri, Dec 23, 2011 at 7:33 AM, Chris Smith <[email protected]> wrote: > > > 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. -- 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.
