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Thread: Fun with DEs

  1. #1

    Default Fun with DEs

    Solve the following, anyone?
    <pre>
    [1 0 1] [e^t ]
    X' = [0 0 2] X + [0 ]
    [0 0 1] [e^-t]
    </pre>
    X and X' are vectors, obviously. I got
    <pre>
    [t] [1] [0]
    e^t(c1 [2] + c2 [0]) + c3 [1]
    [1] [0] [0]
    </pre>
    for the undriven case, which I'm fairly certain of, and
    <pre>
    [te^t(1+K3) + e^t(K1) + .25e^-t]
    [2e^t(K3) + e^-t + (K2 - 2K3) ]
    [e^t(K3) - .5e^-t ]
    </pre>
    for the driven case.

    Take your best shot; I guess I'm just looking to make sure I'm right.
    Last edited by -N-; 05-09-2005 at 09:40 PM. Reason: misprint

  2. #2
    Banned Ism's Avatar
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    Default

    Is this supposed to make sense? And how old r u?

  3. #3

    Default

    Do your OWN DMN homework, lazy@ss! lol . . . the answer is 5
    Jack: How do you know?

    Will: It's more of a feeling really.

    Jack: Well, that's not scientific. Feeling isn't knowing. Feeling is believing. If you believe it, you can't know because there's no knowing what you believe. Then again, no one should believe what they know either. Once you know anything that anything becomes unbelievable if only by virtue of the fact you now... know it. You know?

    Will: No.

    If Demolition Man were remade today

    Huxley: What's wrong? You broke contact.
    Spartan: Contact? I didn't even touch you.
    Huxley: Don't you want to make love?
    Spartan: Is that what you call this? Why don't we just do it the old-fashioned way?
    Huxley: NO!
    Spartan: Whoa! Okay, calm down.
    Huxley: Don't tell me to calm down!
    Spartan: What's gotten into you? 'Cause it sure as hell wasn't me.
    Huxley: Physical relations in the way of intercourse are no longer acceptable John Spartan.
    Spartan: What? Why the hell not?
    Huxley: It's the law, John. And for your information, the very idea that you suggested it makes me feel personally violated.
    Spartan: Wait a minute... violated? Huxley what the hell are you accusing me of here?
    Huxley: You need to leave, John.
    Spartan: But Huxley.
    Huxley: Get out!
    Moments later Spartan is arrested for "violating" Huxley.

    By the way, that's called satire. Get over it.

  4. #4
    Unnatural Devourment's Avatar
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    Quote Originally Posted by -N-
    Solve the following, anyone?
    <pre>
    [1 0 1] [e^t ]
    X' = [0 0 1] X + [0 ]
    [0 0 2] [e^-t]
    </pre>
    X and X' are vectors, obviously. I got
    <pre>
    [t] [1] [0]
    e^t(c1 [2] + c2 [0]) + c3 [1]
    [1] [0] [0]
    </pre>
    for the undriven case, which I'm fairly certain of, and
    <pre>
    [te^t(1+K3) + e^t(K1) + .25e^-t]
    [2e^t(K3) + e^-t + (K2 - 2K3) ]
    [e^t(K3) - .5e^-t ]
    </pre>
    for the driven case.

    Take your best shot; I guess I'm just looking to make sure I'm right.
    Is this work you want other people to do for you?

  5. #5
    Banned Ism's Avatar
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    If you explain the theory and what the it is then I would gladly do it for you.

  6. #6
    Meat Puppet's Avatar
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    I read this thread, and my heart exploded. (I blame fast food)

  7. #7
    Huh? Flower?! What the hell?! Administrator Psychotic's Avatar
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    Oh alright, I'll say it so that no-one else has to: 42.

    Now let's get on with life!

  8. #8
    toothpaste kisses Resha's Avatar
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    MATHS IS BAD. WHATEVER THAT WAS IS BAD. I THINK IT'S EITHER MATHS OR PHYSICS! :weep:
    This subliminal message could be meant for YOU. But it's probably not. Move along ;D

  9. #9
    Banned Caspian's Avatar
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    That's vector analysis, and the only person here who might have a snowball's chance in hell of helping you with it is Dingo Jellybean.

    Stop inflicting college-level math concepts on these 13-18 year old forumers, it's pointless.

  10. #10
    Ominous Wanderer Tech Admin Samuraid's Avatar
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    I took differential equations 2 years ago...and I don't remember how to do that.

  11. #11
    Banned Caspian's Avatar
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    Quote Originally Posted by Samuraid
    I took differential equations 2 years ago...and I don't remember how to do that.
    Because that's not a differential equation?

    =P

  12. #12
    Silent Emotion Rainecloud's Avatar
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    The thread title is misleading. This isn't fun.
    "As the days go by, we face the increasing inevitability that we are alone in a godless,
    uninhabited, hostile and meaningless universe. Still, you've got to laugh, haven't you?"

  13. #13
    Doc Skogs's Avatar
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    Um... solve for what?
    Last edited by Skogs; 05-09-2005 at 05:48 PM.

  14. #14
    Ghost of Christmas' past Recognized Member theundeadhero's Avatar
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    You lured me in with fun, then befuddled me

    2.9999~ = 3
    ...

  15. #15
    Ominous Wanderer Tech Admin Samuraid's Avatar
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    Quote Originally Posted by Caspian
    Quote Originally Posted by Samuraid
    I took differential equations 2 years ago...and I don't remember how to do that.
    Because that's not a differential equation?

    =P
    Actually, it is in a way. Notice the X and X'. The equation expresses a relationship between X and it's derivative, thus it is a differential equation.

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