Re: Nullcline and getting "2" values for y

*To*: mathgroup at smc.vnet.net*Subject*: [mg81509] Re: Nullcline and getting "2" values for y*From*: ben <benjamin.friedrich at gmail.com>*Date*: Wed, 26 Sep 2007 06:41:57 -0400 (EDT)*References*: <fd7s8h$cgc$1@smc.vnet.net>

Dear Sean, I would rather say you are plotting y against fun. fun0=0.3; NSolve[fun == fun0, y] Select[Cases[y /. NSolve[fun == 0.4, y], _Real], (# > 0 && # < 1) &] bye Ben On 24 Sep., 10:24, sean_incali <sean_inc... at yahoo.com> 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