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) | -------------------------------------------------------------------