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Re: Nullcline and getting "2" values for y

  • To: mathgroup at smc.vnet.net
  • Subject: [mg81531] Re: Nullcline and getting "2" values for y
  • From: "Kevin J. McCann" <Kevin.McCann at umbc.edu>
  • Date: Wed, 26 Sep 2007 06:53:19 -0400 (EDT)
  • Organization: University System of Maryland
  • References: <fd7s8h$cgc$1@smc.vnet.net>

Actually what your plot shows is that for a given value of fun, there 
are two y values.

Kevin

sean_incali wrote:
> I have this equation I can plot using the following
> 
> ClearAll["Global`*"]
> 
> 
> fun = (b c y - a y^ n + y^(1 + n))/(b + y^n);
> d = 0.1;
> c = 1;
> b = 10;
> a = 11;
> n = 5;
> ParametricPlot[{fun, (y)}, {y, 0, 1}, PlotRange -> All]
> 
> I am plotting the function "fun" against values of y.
> 
> When I do that I get a curvew that clearly shows that, for a given
> value of y, I should get two value for the function.
> 
> How do I get what they are?
> 
> If I just go..
> 
> d = 0.1;
> c = 1;
> b = 10;
> a = 11;
> n = 2;
> y = 0.5;
> 
> (b c y - a y^ n + y^(1 + n))/(b + y^n)
> 
> I get
> 
> 0.231707
> 
> but starting at y=0 all the way to y= 0.6 or so, there are two values!
> (according to the graph)
> 
> How do I get what those values are?
> 
> 
> Thanks for any input.
> 
> sean
> 
> 


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