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