The equivalent of FindRoot for an interpolating function

*To*: mathgroup at smc.vnet.net*Subject*: [mg37470] The equivalent of FindRoot for an interpolating function*From*: "Philip M. Howe" <pmhowe at lanl.gov>*Date*: Thu, 31 Oct 2002 04:42:16 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

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