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Math Help - solve equation for x with lnx and x

  1. #1
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    solve equation for x with lnx and x

    Hi, is it possible to solve the equation

    y = alnx + bx + c?

    I made it myself as it seems to best model something, and want a computer program i'm writing to be able to calculate x. Is this actually possible?

    Thanks very much in advance for your help,

    James
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  2. #2
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    Quote Originally Posted by jsab500 View Post
    Hi, is it possible to solve the equation

    y = alnx + bx + c?

    I made it myself as it seems to best model something, and want a computer program i'm writing to be able to calculate x. Is this actually possible?

    Thanks very much in advance for your help,

    James
    Do you want to solve for x in terms of y?

    An exact solution will require using the Lambert W-function.
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  3. #3
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    Yes in terms of y.

    How would i go about doing that?

    Thanks
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  4. #4
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    Quote Originally Posted by jsab500 View Post
    Yes in terms of y.

    How would i go about doing that?

    Thanks
    Are you familiar with the Lambert W-function?

    What's wrong with using a numerical procedure to get an approximate value of x for a given value of y .....?
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  5. #5
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    nothing's wrong with it, but if there was a way to just get x = whatever, it would be significantly simpler. I'll have a look at that Lambert-W function.

    Thanks a lot
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