InterpolatingFunction

*To*: mathgroup at smc.vnet.net*Subject*: [mg4972] InterpolatingFunction*From*: André Hautot <ahautot at ulg.ac.be>*Date*: Thu, 17 Oct 1996 00:40:52 -0400*Sender*: owner-wri-mathgroup at wolfram.com

Who can help me? I am studying mathematica and I ask the following question. Suppose I wish to study the function y[t] defined by the oversimplified differential equation sol:=NDSolve[{y''[t]+y[t]==0,y[0]==1,y'[0]==1},y,{t,0,20}, MaxSteps->2000] How can I find ALL the roots of y[t]=0 in the range {t,0,20}? I have tried a lot of things but they don't work. Mathematica user's guide does not help me very much. This kind of question arises when trying to draw Poincare sections of chaotic motions in dynamics. Since I am not yet registered in a mathematica group, please reply to my personal address: ahautot at ulg.ac.be Thank you in advance, AH.