Re: a question about plot a list of functions.

*To*: mathgroup at smc.vnet.net*Subject*: [mg58211] Re: [mg58203] a question about plot a list of functions.*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 23 Jun 2005 05:33:47 -0400 (EDT)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

Use Evaluate K=(2 r/(1-r^2))^2; y=1/(1+K (Sin[x])^2); y=y/.{r->{0.2,0.9,0.995}}; Plot[Evaluate[y],{x,0,10 Pi}]; or Needs["Graphics`"]; Clear[y]; y[x_,r_]:=Module[ {K=(2 r/(1-r^2))^2}, 1/(1+K Sin[x]^2)]; Plot[Evaluate[ y[x,#]&/@{0.2,0.9,0.995}], {x,0,10Pi}, ImageSize->400, PlotStyle->(Hue/@{.6,.4,0}), Ticks->{PiScale[0,10Pi,10],Automatic}]; Bob Hanlon > > From: Zhou Jiang <jiangzhou_yz at yahoo.com> To: mathgroup at smc.vnet.net > Date: 2005/06/22 Wed AM 01:55:51 EDT > Subject: [mg58211] [mg58203] a question about plot a list of functions. > > > I defined a function as > > K=(2 r/(1-r^2))^2; > y=1/(1+K (Sin[x])^2); > y=y/.{r->{0.2,0.9,0.995}} > > Now the result is a list. > I want to plot y vs. x in one figure and I did the following > > Plot[y, {x, 0, 10 Pi}]; > > But Mathematica gave me an error. > I changed it to > > Plot[{y[[1]], y[[2]], y[[3]]}, {x, 0, 10 Pi}]; > > Mathematica gave me a correct plot. Can anyone give me some idea why the error message is given by Mathematica since y is a list and nothing is diffrent from {y[[1]], y[[2]], y[[3]]}? > > Thanks. > > >