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Re: What am I doing wrong with this code?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82572] Re: What am I doing wrong with this code?
  • From: Yaroslav Bulatov <yaroslavvb at gmail.com>
  • Date: Thu, 25 Oct 2007 06:04:30 -0400 (EDT)
  • References: <200710230932.FAA29209@smc.vnet.net><ffn16h$642$1@smc.vnet.net>

When Plot is giving error messages, the first thing to do is to see
what the actual values are, like
Table[((1/y - 1)^(1/2)), {y, 0, 5, .1}]

A useful trick is to plot both real and imaginary parts on the same
graph
Plot[#[(1/y - 1)^(1/2)] & /@ {Re, Im} // Evaluate, {y, 0, 5}]

Yaroslav


On Oct 24, 1:53 am, "Thomas Dowling" <thomasgdowl... at gmail.com> wrote:
> ? Code OK on a Mac using Mathematica 6.0. Do error reoccur after restart?
>
> Tom Dowling
>
> On 10/23/07, sean_incali <sean_inc... at yahoo.com> wrote:
>
>
>
> > I think I'm having a brain fart. Seriously...
>
> > Plot[{1/(1 + y^2), (1/y - 1)^(1/2)}, {y,  0, 5}]
>
> > What is wrong with that code? Maybe it's not solvable in mathematica?
>
> > I'm trying to plot nullclines of a system of ODEs. and those function
> > up there are them. I just can't get mathematica to plot them in the
> > same graph.
>
> > I get an error message saying...
>
> > >From In[22]:=
> > (1/y - 1)^(1/2)  is not a machine-size real number at y =
> > 1.0000001666666667`.
>
> > Any help is appreciated.
>
> > sean




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