Plotting x^(1/3), etc.

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Plotting x^(1/3), etc.*From*: jkc at keller.mines.colorado.edu (Jack K. Cohen)*Date*: Thu, 16 Apr 92 08:52:11 MDT

A fix for making (-1)^(1/3) evaluate as -1 instead of as the root on the first sheet is: protected = Unprotect[Power] x_^r_Rational := (-(-x)^(1/Denominator[r]))^Numerator[r] /; Negative[x] && OddQ[Denominator[r]] Protect[Evaluate[protected]] Be aware that the complex evaluation is NOT a bug--as previously noted in this news group, it makes Power consistent with the other complex valued functions. However, in Calculus classes we do NOT want the complex values. Hence I suggest putting the above in some suitable package rather than making it global to your environment by putting it in init.m. I have written a Calculus.m package containing various utilities useful for my classes and that's where I have it. I am willing to share Calculus.m with you, as long as you understand it isn't intended to be robust, professional level code. Send me e-mail, if you want it.