Re: Not all points plot on my graph...

*To*: mathgroup at smc.vnet.net*Subject*: [mg105185] Re: Not all points plot on my graph...*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Tue, 24 Nov 2009 05:45:32 -0500 (EST)*References*: <hedte4$lsn$1@smc.vnet.net>

Just try f[-3]//N. You'll see it's imaginary (one of the three possible roots). Cheers -- Sjoerd On Nov 23, 1:59 pm, davef <davidfrick2... at yahoo.com> wrote: > Why is it when I write this... > > Clear[f, x] > f[x_] = (x + 2)^(2/3) > Plot[f[x], {x, -3, 0}, PlotRange -> {{-3, 0}, {-4, 4}}] > f[-3] > > .. I get no values show in the graph for x<-2 even though f[-3] > evaluates to (-1)^(2/3). > > (-1)^(2/3) evaluates as f[-3]=1 so why wouldn't the point (-3,1) plot > on my graph?