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Math Help - Help me determine the Laplace Transform and the ROC?

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    Help me determine the Laplace Transform and the ROC?

    Help me determine the Laplace Transform and the ROC?-laplace.jpg

    Last edited by CaptainBlack; December 29th 2011 at 06:27 AM.
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    Super Member ILikeSerena's Avatar
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    Re: Help me determine the Laplace Transform and the ROC?

    Hi essedra!

    The Laplace transform is given by:

    \mathcal{L}_t[\chi(t)](s) = \int_0^\infty \chi(t) e^{-st} dt

    Is this also the Laplace transform you are supposed to calculate?
    I ask since it is a bit strange to see u(t+3) as part of the function...

    Can you evaluate that integral?
    Last edited by ILikeSerena; December 29th 2011 at 03:44 PM.
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    Re: Help me determine the Laplace Transform and the ROC?

    WolframAlpha to the rescue.
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    Super Member ILikeSerena's Avatar
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    Re: Help me determine the Laplace Transform and the ROC?

    Quote Originally Posted by Ackbeet View Post
    WolframAlpha to the rescue.
    Aww... you take all the fun out of it!

    My problem with u(t+3) is that it is the Heaviside step function that "steps" at t=-3, which is out of bounds for the integral.
    In other words, it does not do anything!?
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    Re: Help me determine the Laplace Transform and the ROC?

    Quote Originally Posted by ILikeSerena View Post
    Aww... you take all the fun out of it!

    My problem with u(t+3) is that it is the Heaviside step function that "steps" at t=-3, which is out of bounds for the integral.
    In other words, it does not do anything!?
    I suppose that's true of the standard one-sided LT.
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