Re: Using NDSolve and Finding a specific Value

*To*: mathgroup at smc.vnet.net*Subject*: [mg85375] Re: Using NDSolve and Finding a specific Value*From*: "Kevin J. McCann" <Kevin.McCann at umbc.edu>*Date*: Thu, 7 Feb 2008 22:28:51 -0500 (EST)*Organization*: University System of Maryland*References*: <foek87$i3s$1@smc.vnet.net>

I am sure that you will get a lot of responses, but here is mine: try: eye[t_] = i[t] /. sols[[1]] Then eye[3.8] 0.324902 Kevin Note the [[1]]. The InterpolationFunction answer is in double wigglies: {{....}}. The [[1]] pulls it out so there is no enclosing {}. Tara.Ann.Lorenz at gmail.com wrote: > Hello. > > I am having an issue related to the NDSolve function (I am using > Version 6). The following example illustrates the problem I am > having: > > Input: > sols = NDSolve[{i'[t] == (1/8.516011) (-i[t] + 0.596120754), > i[1] == 0.219319}, i[t], {t, 1, 4}] > > Output: > {{i[t]->InterpolatingFunction[{{1.,4.}},<>][t]}} > > I then would like to solve i[t] for t=3.8 > According to the Mathematica website, I should be able to enter the > following input to receive my answer: > > i[3.8]/.sols > > However, my output is simply i[3.8] and not a numerical value. What > else can I try to get a numerical value from the interpolating > function. > > I appreciate any feedback. Thank you > > > -- Kevin J. McCann Research Associate Professor JCET/Physics Physics Building University of Maryland, Baltimore County 1000 Hilltop Circle Baltimore, MD 21250