Re: calculate Recurrence Equations
- To: mathgroup at smc.vnet.net
- Subject: [mg68747] Re: [mg68713] calculate Recurrence Equations
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Fri, 18 Aug 2006 03:11:47 -0400 (EDT)
- Reply-to: hanlonr at cox.net
- Sender: owner-wri-mathgroup at wolfram.com
Add memory to the definition Clear[anteil1]; anteil1[0]=1; anteil1[n_Integer?Positive]:= anteil1[n]= anteil1[n-1]+(anteil1[n-1]*5-1)/100; anteil1[n_Integer?Negative]:= anteil1[n]=(1/105)*(100*anteil1[n+1]+1); anteil1[30]//Timing//N {0.002837 Second,3.65755} Clear[anteil2]; anteil2[n_]=anteil2[n]/.RSolve[{ anteil2[n]==anteil2[n-1]+(anteil2[n-1]*5-1)/100, anteil2[0]==1},anteil2[n],n][[1]] (1/5)*(1 + 4^(1 - n)*(21/5)^n) anteil2[30]//Timing//N {0.000229 Second,3.65755} Plot[anteil2[n],{n,-10,10}, PlotStyle->Blue,ImageSize\[Rule]432, Epilog->{Red, AbsolutePointSize[4], Point/@Table[{n,anteil1[n]},{n,-10,20}]}]; Bob Hanlon ---- Frank Hechtner <frank.hechtner at rub.de> wrote: > hi, > > i?m in trouble with my Recurrence Equations: > > i?ve defined the following function > > anteil[0] = 1 > anteil[n_] := anteil[n - 1] + (anteil[n - 1]*5 - 1)/100 > > i want mathematica to calculate the values for anteil[30] and so on. > > Unfortunately mathematica needs for this calculation over 2 hours (and > is still running, athlon x2 4600, 2 gb ram). > > I don?t see where are the difficulties for mathematica... > > Thanx for your help > > frank >