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  1. #1
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    Help w/simple excel log formula

    Hi to all,

    I am having difficulty in getting the following formula to run in excel 2003:

    10 x Log (base 10) (x/y^2).....in this case "x" (column F) and "y" (column G) are found in columns on the same
    worksheet/page, when I enter my formual for this it runs without error but I am getting the wrong result. A

    Attached is a copy of the worksheet.... column "H" contains my results and column "K" contains the correct results.

    Any assistance will be appreciated...

    Marty
    Attached Files Attached Files
    Regards,
    Marty

    "Aerodynamics Is For Those Who Cannot Build Engines" - Enzo Ferrari

  2. #2
    WS Lounge VIP sdckapr's Avatar
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    =10*LOG10(F2/G2*G2)
    is the same as
    =10*LOG10(F2)

    since dividing by G2 and then multiplying by G2 "cancels" it out.You either want:=10*LOG10(F2/G2^2)

    or
    =10*LOG10(F2/G2/G2)

    or
    =10*LOG10(F2/(G2*G2))

    Steve

  3. #3
    WS Lounge VIP sdckapr's Avatar
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    I just noticed that the formula you list will not give the answers in K.

    To ge teh answers you need:=LOG((F2/G2)^2)
    which is equicvalent to:
    =2*LOG(F2/G2)

    Steve

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    mojave1 (2012-05-31)

  5. #4
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    Hi Steve,

    thanks for the assistance, yet I do not see how 10 x log(base 10) x (Y/S squared) becomes the above...clearly it works, yet why?
    Regards,
    Marty

    "Aerodynamics Is For Those Who Cannot Build Engines" - Enzo Ferrari

  6. #5
    WS Lounge VIP sdckapr's Avatar
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    It doesn't. Either your formula or your "answer" is wrong.

    To get the answers you indicate as "right", the factor of 10 is not used and it is not x/y it is (x/y)

    [Note in excel Log10(x) = Log(x,10) = Log(x), the log function defaults to base 10 if no base is indicated]

    Steve

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    mojave1 (2012-06-02)

  8. #6
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    my sentiments exactly, thatnks for the assistance Steve....
    Regards,
    Marty

    "Aerodynamics Is For Those Who Cannot Build Engines" - Enzo Ferrari

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