Re: intelligent Integrate
- To: mathgroup at yoda.physics.unc.edu
- Subject: Re: intelligent Integrate
- From: withoff
- Date: Fri, 22 Jan 93 09:35:19 CST
> Subject: intelligent Integrate > > Hi MathGroup, > > The input > > Integrate[ f'[x] g[x] + f[x] g'[x],x] > gives f[x] g[x]. I think by a rule associated with Integrate. > But > Integrate[f'[x] g[x],x] + Integrate[f[x] g'[x],x] > also produces > f[x] g[x]. This is quite nice, but I do not understand how this > happens by looking at the standard Mma evaluation procedure. > Is there a hidden rule for Integrate over Plus? > > Thanks for an answer, > > Michael Trott > > trott at physik.tu-ilmenau.de This works out because Integrate[f[x] g'[x],x] evaluates to f[x] g[x] - Integrate[g[x] f'[x], x] and the two unevaluated integrals cancel. There are no "hidden" rules for Integrate over Plus. Integrate returns many partially integrated results for exactly this reason. Dave Withoff withoff at wri.com