Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.



Re: wrong result when computing a definite integral
Posted:
Jan 11, 2013 10:23 PM


On Thursday, January 10, 2013 8:38:22 PM UTC6, Dexter Filmore wrote: > hi group, > > > > i run into this problem today when giving a bunch of easy integrals to mathematica. > > here's a wolfram alpha link to the problem: > > http://www.wolframalpha.com/input/?i=Integrate%5BExp%5BI+Sqrt%5B3%5Dy%5D%2C%7Bx%2C2Pi%2C2Pi%7D%2C%7By%2CPi%2CPi%7D%5D# > > > > the integrand does not depend on the 'x' variable, the inner integration should only result in a factor of 4Pi, and the correct result is a real number, yet the below integral gives a complex number which is far off from the correct value: > > Integrate[Exp[I Sqrt[3] y], {x, 2 Pi, 2 Pi}, {y, Pi, Pi}] > ((4 I (1 + E^(2 I Sqrt[3] Pi)) Pi)/Sqrt[3]) > > > > from some trial and error it seems the result is also incorrect for noninteger factors in the exponential.
Thank you for the example. I reported this as a bug. I apologize for any inconvenience it may have caused.
Daniel Lichtblau Wolfram Research



