Re: Using a logical Or in the function definition

*To*: mathgroup at smc.vnet.net*Subject*: [mg86711] Re: Using a logical Or in the function definition*From*: giovanni resta <g.restaCUT at CUTiit.cnr.it>*Date*: Wed, 19 Mar 2008 05:24:18 -0500 (EST)*References*: <fro39q$i8a$1@smc.vnet.net>

ahallam at iastate.edu wrote: > I would like to use Or in the function definition as in > > ab[ Or[r_Integer,r_Rational], Or[s_Integer,s_Rational] ]:=r/s; > > In other words, I want the function to take integers or ratios of > integers as arguments, but not real numbers which are not rational. Probably I do not understand your problem, but every Integer is also Rational, so you can use something like ab[r_/;Element[r,Rationals], s_/;Element[s,Rationals]] := r/s; instead of Element[r,Rationals] you can type r [Esc]el[Esc] Rationals where [Esc] is the Esc key. g. g.