MathSource contains a package entitled Declare.m which attempts to provide an easy and effective way to declare variables real, positive, even, etc. I wonder if any of you out there have tried it? I would like to hear from you. Thanks.
By the way, my copy of this package does not have the author's name. I think the package needs some work so I would like to contact the author to see if he/she has done any more with it. As it stands the package has some bugs: here's one
results in an error message using Mma 2.2.2 on a PowerMac.