Re: help: recursive functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg32635] Re: [mg32616] help: recursive functions*From*: BobHanlon at aol.com*Date*: Fri, 1 Feb 2002 02:02:41 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

In a message dated 1/31/02 2:13:14 AM, Okke at NOSPAMtref.nl writes: >I'm having some problems with a recursive function. >Could somebody please help me by telling me how I >should enter such a function? > >tia, > >This is what I've done so far: > >f[n_]:=Sin[Pi*n*(0.05+(0.0005*n))] >y[n_]:=1.5*y[n-1]-0.85*y[n-2]+f[n] > >I'm trying to Plot[y[n],{n,0,320}] but that gives me >an error: $RecursionLimit::reclim: Recursion depth of 256 exceeded. > >btw, is there an option to fill the area under the sine? > You need to define some stopping values for the recursion. I also recommend adding "memory" to the recursion to speed it up. For example, f[n_]:=Sin[Pi*n*(0.05+(0.0005*n))]; y[0] = y[1]=0; y[n_Integer]:= y[n]=1.5*y[n-1]-0.85*y[n-2]+f[n]; data=Table[y[n],{n,0,320}]; ListPlot[data, PlotJoined->True, ImageSize->350]; Needs["Graphics`FilledPlot`"]; FilledListPlot[data, PlotJoined->True, Fills->RGBColor[1, 0, 0], ImageSize->350]; Bob Hanlon Chantilly, VA USA