> How can I call a variable a real number without assigning it a real value? I'm using Mathematica 3.0, and I don't want Mathematica to think of some variables, like ''a'' and ''b'', as just symbols, but instead, treat them as reals which haven't been given values yet. Any help you can offer would be greatly appreciated.
Mathematica does not have any facilities for declaring a variable to be real, integer, positive, etc.
You may want to look into the package Miscellaneous`RealOnly` which may provide you with what you want. Or you can leave things as they are and extract real values from the results of your calculations.