Re: Re: The graph of (x + 2)^(1/5) + 4 not plotted correctly

*To*: mathgroup at smc.vnet.net*Subject*: [mg103938] Re: [mg103926] Re: The graph of (x + 2)^(1/5) + 4 not plotted correctly*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Tue, 13 Oct 2009 23:17:45 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <868306d90910120643u7f1c2299v2cd1845508dc85b7@mail.gmail.com> <200910131118.HAA29247@smc.vnet.net>*Reply-to*: murray at math.umass.edu

Could you please just tell us what you think is wrong with the plot that Mathematica provides? I ask because when I point my browser to the link you provide... (1) I get a large number of annoying (and potentially dangerous) 3rd-party ad-generating items on the URL page that clamor to be allowed to do their thing. (2) The plot finally displayed is of something entirely different -- of exp(-x^2) and its first two derivatives. As to the function (x + 2)^(1/5) + 4 that you asked about: Did you just try something like the following? Plot[(x + 2)^(1/5) + 4, {x,-7,5}] If so, then you were probably surprised that the graph ended on the left at x == -2. And that is precisely what Mathematica should be expected to do. After all, Mathematica "wants" numbers to be complex when they can be. And z^(1/5) denotes the PRINCIPAL 5th-root of z, so that when z is negative, you do NOT get a negative real number, but rather the non-real, complex principal 5th-root. If you want the high school/calculus variety 5th-root function, then you need to finesse this. For example: f[x_] := Sign[x + 2] Abs[x + 2]^(1/5) + 4 Plot[ f[x], {x,-7,5}] (You could use Piecewise instead.) victor chg wrote: > Here is the link to the image: > http://tinypic.com/view.php?pic=veae6u&s=4 > > Victor Chg -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Re: The graph of (x + 2)^(1/5) + 4 not plotted correctly***From:*victor chg <kindlychung@gmail.com>