Error(?) in Limit Evaluation
- To: mathgroup at yoda.physics.unc.edu
- Subject: Error(?) in Limit Evaluation
- From: NATARAJ at ucis.vill.edu (Nat C. Nataraj)
- Date: Tue, 5 Jul 1994 09:51 EST
Hello Folks!
I am new to Mathematica (although I have used Macsyma for almost ten
years), and the very first thing I tried gave me an erroneous answer.
It was a definite integral, and quite involved. After fooling around
for two days, I reduced the possible Mma problem down to the following.
In: Limit[ArcTan[Tan[x]], x -> Pi/2]
gives
Out: -Pi/2
as the answer, which is of course wrong. The reason is that tangent
is a multivalued function, and the limit really depends upon the direction
of approach.
However, this limit was buried inside the integral, and Mma did not even
give me a warning. The only reason I knew something was amiss was because
I knew what to expect from the physics of the problem.
By the way, I tried the above on Macsyma, and it gave me `No Limit Exists'
as the answer.
Am I missing something? Is there some control parameter I should
have set? Any comments will be most appreciated.
Thanks.
Nat
-------------------------------------------------------------------
| Dr. "Nat" C. Nataraj Off: (610) 519-4994 |
| Department of Mechanical Engineering FAX: (610) 519-7312 |
| Villanova University |
| Villanova, PA 19085 |
| |
| e-mail: nataraj at vuvaxcom (bitnet) |
| nataraj at ucis.vill.edu (internet) |
-------------------------------------------------------------------