Results 1 to 3 of 3

Math Help - Finding the period of a periodic function

  1. #1
    Member
    Joined
    Jan 2010
    Posts
    133

    Finding the period of a periodic function

    Hello Everyone!

    I think my question would go here. Is there a method to find the period of a given periodic function? Say: f(t)=\cos (2\pi f_a t)\cos (2\pi f_b t) where b is not necessarily an integer multiple of a

    Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Sep 2011
    Posts
    24

    Re: Finding the period of a periodic function

    Is this anything to do with wiki: Beat (acoustics)?

    2 cos (2丌f at) cos (2丌f bt) = cos (2丌f a -2丌f b)t + cos (2丌f a +2丌f b)t

    f beat = f1 - f2

    f beat = (f a +f b) - (f a - f b) = 2f b

    period, T = 1/(2f b)? Is it?
    Last edited by BookEnquiry; October 5th 2011 at 12:13 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4

    Re: Finding the period of a periodic function

    Quote Originally Posted by rebghb View Post
    Hello Everyone!

    I think my question would go here. Is there a method to find the period of a given periodic function? Say: f(t)=\cos (2\pi f_a t)\cos (2\pi f_b t) where b is not necessarily an integer multiple of a

    Thanks!
    This is not periodic unless (f_a+f_b)/(f_a-f_b) is a rational number. If this ratio is rational the period of f(t) can be found by writing it in canonical form

    CB
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 0
    Last Post: September 12th 2010, 01:51 PM
  2. Average Value Function and Equivalent Periodic Function
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: February 14th 2010, 04:31 AM
  3. Finding the period of sin function
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: December 8th 2009, 01:38 PM
  4. Finding the period of a function?
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: November 9th 2009, 09:39 AM
  5. Finding the period (n)
    Posted in the Algebra Forum
    Replies: 4
    Last Post: May 2nd 2007, 10:31 PM

Search Tags


/mathhelpforum @mathhelpforum