Mathematica confusion

*To*: uiucuxc!yoda.ncsa.uiuc.edu!mathgroup*Subject*: Mathematica confusion*From*: uiucuxc!uthvm1.bitnet!AN123651*Date*: Mon, 25 Jun 90 14:54:41 CST

Thanks to the many people who have responded to my earlier posting. Let me see if I can be more clear, and refrain from embarassing myself further. When I enter the expression (1/x) (1/x^2)^(1/x^2 -1) mma simplifies it to x^(-1 - 2 (-1 + x^(-2))) Now, consider x = -2 (not -1 as I mistyped previously). In the first expression, x is squared before any roots are taken, so it is natural to expect a real answer. In the second case, a root of -2 is taken and a complex answer is no surprise. mma's simplification effects the choice of the branch cut. This is not a bug. The question of branch cuts is difficult. Instead, let me post this as a query - how can I get mma to take the cut I want? Note that mma is not entirely consistent on this point: (1/x) (1/x^2)^(1/x^2 -1) /. x-> -2 and f[x_] := (1/x) (1/x^2)^(1/x^2 -1) f[-2] return different answers. E. Neely Atkinson AN123651 at UTHVM1.BITNET neely at mdaali.cancer.utexas.edu