defining number type

*To*: mathgroup at yoda.physics.unc.edu*Subject*: defining number type*From*: "Hamburger Dani" <dani at zernike.fh.huji.ac.il>*Date*: Sun, 24 Apr 1994 08:25:57 +0000

I would like to simplify certain results by declaring the relevant variables to take on integer values only. For example: In[1]:= <<Algebra`SymbolicSum` In[2]:= Sum[m!/(k! (m-k)!),{k,0,m}] m 2 m! Out[2]= ------------ Gamma[1 + m] and this should simplify to 2^m if m is known to be integer valued. How does one do this? Simple minded approaches such as IntegerQ[m]^=True, m /: IntegerQ[m]=True, or Declare[m,Integer] don't do it. (In fact Declare.m adds trouble: it somehow interferes with the Algebra`SymbolicSum` package. After loading both, most symbolic sums are no longer evaluated, including the one above). Another question: how does one implement the operator (x d/dx)^k ? Thanks, -- Daniel Fritz Haber Center for Molecular Dynamics Hebrew University of Jerusalem