RE: The equivalent of FindRoot for an interpolating function
- To: mathgroup at smc.vnet.net
- Subject: [mg37476] RE: [mg37470] The equivalent of FindRoot for an interpolating function
- From: "Florian Jaccard" <jaccardf at eicn.ch>
- Date: Fri, 1 Nov 2002 01:42:44 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hello Philip ! You can do it like this : In[1]:=NDSolve[{y'[t] == 1-y[t], y[0]==0}, y[t], {t, 0, 20}] In[2]:=y[t_]=y[t]/.%[[1]] In[3]:=Plot[y[t],{t,0,10},PlotRange->{0,2}] In[4]:=FindRoot[y[t]==.999,{t,1}] Meilleures salutations Florian Jaccard EICN-HES e-mail : jaccardf at eicn.ch -----Message d'origine----- De : Philip M. Howe [mailto:pmhowe at lanl.gov] Envoyé : jeu., 31. octobre 2002 10:42 À : mathgroup at smc.vnet.net Objet : [mg37470] The equivalent of FindRoot for an interpolating function Hi Folks, I wish to find the value of the independent variable in an interpolating function that makes the dependent variable assume some value of interest. For example, sol = NDSolve[{y'[t] == 1-y[t], y[0]==0}, y, {t, 0, 20}] fy = y/.sol[[1]] produces an interpolating function. I would like to extract the value of t that yields a value of 0.99 or 0.9999 (say) for y. Is there a straightforward way of doing this? Thanks in advance for the help. Regards, Phil -- Philip M. Howe Program Manager, Stockpile Surety Los Alamos National Laboratory (505) 665-5332 (505) 667-9498 Fax: 505-665-5249 email pmhowe at lanl.gov Mail Stop P945