Re: Integrate with If

*To*: mathgroup at smc.vnet.net*Subject*: [mg22275] Re: Integrate with If*From*: "Johan Berglind,5879" <johanbe at chl.chalmers.se>*Date*: Mon, 21 Feb 2000 20:00:45 -0500 (EST)*Organization*: Chalmers University of Technology*References*: <88g62h$4mq@smc.vnet.net> <88jtvv$9n3@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

> > The "If" construct is an impropper argument for Integrate, see the > online-help: > (...) > Integrate can evaluate integrals of rational functions. It can also > evaluate integrals that involve exponential, logarithmic, trigonometric > and inverse trigonometric functions, so long as the result comes out in > terms of the same set of functions. > (...) > Thank you, Harald. As you and many others have pointed out, If is not suited for use in Integrate. It does, however work most of the time; Integrate[If[Sin[t]>0,1,0], {t,-Pi/2,Pi/2}] gives the correct answer. (The critical point seems to be -Pi) And it seems to be fairly efficient. (Try using it in FourierSeries.) My point is that either should If work in Integrate all of the time (and I believe that is the ambition of Wolfram) or Mathematica should at least produce a warning. Johan.