Adding and Integrating Interpolation Functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg103801] Adding and Integrating Interpolation Functions*From*: "Bayers, Alexander" <alexander.bayers at baml.com>*Date*: Wed, 7 Oct 2009 07:00:46 -0400 (EDT)

I have two interpolation functions, firstinterp and secondinterp, that I wish to add. They are defined symbolically, i.e. a = {1, 2, 3, 4, 5} b = {b1, b2, b3, b4, b5} c = {c1, c2, c3, c4, c5} firstinterp = Interpolation[Transpose[{a, b}], InterpolationOrder -> 1] secondinterp = Interpolation[Transpose[{a, b}], InterpolationOrder -> 1] newinterp[t_]:= firstinterp[t] + secondinterp[t] While I can evaluate newinterp at any point, and I am able to integrate firstinterp[t] and secondinterp[t], when I run Integrate[newinterp[t], {t, 2, 3}] I receive (InterpolatingFunction[{{1, 5}}, <>][t] + InterpolatingFunction[{{1, 5}}, <>][t]) dt under an integral sign, rather than the evaluated value. Does anyone know how to get this to integrate to its real value? Thanks, Alex

**Follow-Ups**:**Re: Adding and Integrating Interpolation Functions***From:*DrMajorBob <btreat1@austin.rr.com>