Re: Q: How to force an Equal[]
- Subject: [mg3363] Re: [mg3332] Q: How to force an Equal[]
- From: richard at seuss.math.wright.edu (Richard Mercer)
- Date: 2 Mar 1996 11:17:37 -0600
- Approved: usenet@wri.com
- Distribution: local
- Newsgroups: wri.mathgroup
- Organization: Wolfram Research, Inc.
- Sender: daemon at wri.com
> Hi there, > > this should be a nice relaxing one. How can I force Mma > to evaluate the equal expression, regardless of what > values Word or Number stand for. I just want a false in > the second case (y1==y2). > ...... I learned a long time ago to use == ONLY for numerical equalities and use === for other things. The truth is not quite that simple, but this simple rule will generally keep you out of trouble. Also avoid using == with exact numerical expressions, e.g. with a = 2 + Sqrt[2]; b = 2/(2 - Sqrt[2]); a == b does not evaluate. a === b gives False N[a] == N[b] gives True So y1 === y2 ought to do the trick here. (Haven't tried it.) You can also use TrueQ[y1==y2] to force a decision. This always yields True or False, defaulting to False. Richard Mercer