Re: How to enter an integral in a formula and have mathematica *not*

*To*: mathgroup at smc.vnet.net*Subject*: [mg109000] Re: How to enter an integral in a formula and have mathematica *not**From*: gekko <pfalloon at gmail.com>*Date*: Sat, 10 Apr 2010 06:51:28 -0400 (EDT)*References*: <hpkgjc$7vn$1@smc.vnet.net>

On Apr 8, 10:01 pm, Jim Rockford <jim.rockfo... at gmail.com> wrote: > I have a certain integral, part of a larger expression, that can be > expressed in terms of incomplete gamma functions by Mathematica. But > in carrying out the definite integral and forcing it to be written in > terms of gamma functions, this introduces branch points and other > unnecessary complications. I want the integral left alone and > evaluated numerically, but I still want to express the general formula > for this large expression with the unevaluated integral in place. > > For example, I'd like > > f[x_] = (stuff) + int_{0}^{1} (g[s,x]) ds > > where the definite integral is expressed in the usual Mathematica > notation. > > What I do *not* want Mathematica to do at this stage is to do the > integral analytically and write it in terms of special functions. > Instead, I just want to later make a list of values for f[x] and > have the integral done numerically. > > How can I program this? > > Thanks, > Jim You'll probably get at least a half-dozen replies along these lines, but just in case: one way to achieve what you want would be to make the definition of "f" only match numerical values, e.g. f[x_?NumericQ] := stuff[x] + Integrate[g[s,x], {s,0,1}] If it should only match for Integer arguments, you could use f[x_Integer] := ... instead. Cheers, P.