Re: Operations on InterpolatingFunction

*To*: mathgroup at smc.vnet.net*Subject*: [mg100855] Re: Operations on InterpolatingFunction*From*: dh <dh at metrohm.com>*Date*: Tue, 16 Jun 2009 21:52:04 -0400 (EDT)*References*: <h0t846$r6n$1@smc.vnet.net>

Hi Porscha, obviously there are only rules to integrate InterpolatingFunctions but none for functions of InterpolatingFunctions. You could add such rules, but it is easier to write the "function of a InterpolatingFunction" as an InterpolatingFunction. E.g. your case: ifun2 = FunctionInterpolation[ifun[x]^2, {x, 0, Pi}] Now you can integrate ifun2: Integrate[ifun2[t], t] hope this helps, Daniel Porscha Louise McRobbie wrote: > Hi, > > Solving a simple differential equation: > ifun = First[ > u /. NDSolve[{u''[t] + u[t] == 0, u[0] == 0, u'[0] == 1}, > u, {t, 0, \[Pi]}]] > > returns the InterpolationFunction object, as expected. I can integrate > this function (and obtain another InterpolatingFunction to be plotted, > etc.) by: > > Integrate[ifun[t], t] > > 1. Why doesn't the following produce an InterpolatingFunction in the same way? > > Integrate[ifun[t]^2, t] > > 2. How can I normalize the solutions found using NDSolve? > Norm[ifunt[t]] doesn't work... > > Thanks for any help. > > > > > >