MathGroup Archive 1995

[Date Index] [Thread Index] [Author Index]

Search the Archive

Peculiar behavior of Integrate

Can anyone explain this to me?  This comes from Problem G.1.b.iii of problem
set 2.03 of Davis, Porta and Uhl's Calculus and Mathematica:

If I execute

100 + Integrate[(160 E^t)/(0.5 + E^t)^2,{t,0,T}]

Mathematica does it in a wink.  If I execute

100 + Integrate[(160 E^t)/(1/2 + E^t)^2,{t,0,2400}]

Mathematica does it quick as a wink.  (This is on a Power Mac 9500/132;
your winks may vary.)

But if I execute

100 + Integrate[(160 E^t)/(0.5 + E^t)^2,{t,0,2400}]

then Mathematica grinds away... and grinds away... and so far I haven't had
the patience to outwait it.  When I interrupt the kernel it takes almost a
minute to back out of whatever it's doing.

What's it doing?  Is this some local user-preference which is causing this?
Can anyone verify similar behavior on other platforms?

This is Mathematica for the Power Macintosh (the printing-magnifi-
cation-but-fix version).

I asked the student whether she had made the proper propitiary sacrifices
before sitting down at the computer, and she swore she had ;-)

--Ron Bruck

  • Prev by Date: Re: Scientific Web - Speedcomparison Mathematica 2
  • Next by Date: Re: Positive[a] = True ???
  • Previous by thread: 3D calculations
  • Next by thread: (fwd) INVITATION: Preregister for ICM98 !!! IMU and ICM98-servers in action