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]]
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.
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