Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I Why this triple integral equals zero?

  1. Sep 5, 2016 #1
    Hello everyone, I have the this inquiry:

    if I compute de following integral:
    by numerical methods I get cero as a result. I used Maxima and Mathematica and their functions for numerical integration give me an answer equal to cero.
    But, if I apply transformation with spherical coordinates the result turns out to be equal to pi^2 / 40.
    I can't seem to find an explanation for this. Could any of you guys give me a hand with this? Thank you in advance.
  2. jcsd
  3. Sep 5, 2016 #2


    Staff: Mentor

    Well we'd need to see how you transformed the integral and its limits into spherical coordinates before we could even attempt to say what happened.

    One question I had was whether you transformed the dxdydz properly or not.


    Where you can see that dXdydz transforms into:

    ##dV = \rho^2 sin \theta d\rho d\theta d\phi##
    Last edited: Sep 5, 2016
  4. Sep 6, 2016 #3


    User Avatar

    Staff: Mentor

    The thread title asks why this is zero, which is quite easy to show. The first two integrations, over z and y, are trivial to do, and the result is an odd function of x.
  5. Sep 6, 2016 #4
    Thank you so much for your answers, I rechecked what I did this morning and I found out what happens when calculating the integral in spherical coordinates.

    Again, thank you so much for your time and cooperation, you guys rock!!!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted