Results 1 to 5 of 5

Math Help - solve by method of convolutions....

  1. #1
    Senior Member
    Joined
    Aug 2009
    Posts
    349

    solve by method of convolutions....

    ok so here is the problem, which by the way i thought was very straight forward...




    ok so i thought that i would just multiply the transforms by each other, but thats not what my book is showing.

    for f(t)= e^-t and g(t)= cos t

    so i tried multiplying (1/s+1)*(s/s^2+1)?

    so where did i go wrong?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Aug 2009
    Posts
    349
    for this problem please ignore the f(t) and g(t)..this was my attempt at the problem. the question is asking me to solve the problem by method of convolutions, which I am unsure of how to do. i hope i didnt confuse ne one with this posting..
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by slapmaxwell1 View Post
    ok so here is the problem, which by the way i thought was very straight forward...




    ok so i thought that i would just multiply the transforms by each other, but thats not what my book is showing.

    for f(t)= e^-t and g(t)= cos t

    so i tried multiplying (1/s+1)*(s/s^2+1)?

    so where did i go wrong?
    Note that



    where f(t) = .... and g(t) = ....
    Last edited by Chris L T521; April 25th 2011 at 09:14 PM. Reason: fixed LaTeX image compilation complication.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member
    Joined
    Aug 2009
    Posts
    349
    <--- ok kool, i was wondering where the 1/s was coming from.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Santa Cruz, CA
    Posts
    2,844
    Thanks
    3
    Quote Originally Posted by mr fantastic View Post
    I know the latex is not working. I don't know what the problem is. But I'm sure you can figure out what I posted.
    It turns out that it didn't like the f(t)*g(t) part. So I replaced it with f(t)\ast g(t) and it turned out alright. This may be the case because this is supposed to be a link of some kind, and having * in a link is a bit bizarre.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Well Definedness and C^infinity Closure of Convolutions
    Posted in the Differential Geometry Forum
    Replies: 0
    Last Post: March 5th 2012, 04:58 PM
  2. How to evaluate these convolutions:
    Posted in the Calculus Forum
    Replies: 7
    Last Post: October 20th 2011, 12:34 PM
  3. Convolutions
    Posted in the Differential Geometry Forum
    Replies: 3
    Last Post: April 21st 2011, 07:56 AM
  4. Inverse Fourier Transform using convolutions
    Posted in the Calculus Forum
    Replies: 2
    Last Post: May 17th 2010, 02:18 PM
  5. Replies: 3
    Last Post: November 3rd 2007, 01:43 PM

Search Tags


/mathhelpforum @mathhelpforum