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Thread: excel input

  1. #1
    Associate Engineer
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    Nov 2013
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    excel input

    hi.

    just making a road design spreadhseet. anyone know how I can put this formula into excel?

    =max{100, 0.475[219 - 211(logCBR + 58(logCBR)2]log(14DESA)}


    keep getting errors.

    thanks

  2. #2
    Lead Engineer
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    Unfortunately, I see many errors.
    1. Have you assigned reference cells with the CBR and DESA titles? If not, in the equation you need to reference cell locations with the values for those two inputs.
    2. The correct format for logarithms in excel is LOG(reference cell,base) and if you you want a log to the base 10 then the correct format is LOG10(reference cell)
    Note: To find excel all correct function formats use the (fx) button at the front of the formula entry line above the spreadsheet grid
    3. An (*) multiplier operator is required between the formula elements to be multiplied i.e. = max(100,.475*(219-211*LOG10(CBR ref cell)+58*LOG10(CBR ref cell*2))*LOG10(14*DESA ref cell))
    4. If you intend for your log(CBR)2 to mean log(CBR) squared then the correct operator is log( )^2 rather than log( )*2

    5. One important note on the above enclosing brackets, excel only recognises ( ) parentheses for formula enclosures so the [] and {} enclosures you used must be replaced by stacked parentheses as shown in 3. above.
    Last edited by JAlberts; 11-26-2013 at 02:30 PM. Reason: Added 5. for clarification of use of parentheses

  3. #3
    Associate Engineer
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    thankyou so much Ill try it out now

  4. #4
    Associate Engineer
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    How do I know what log base to use?

    This is just the general Minimum thickness of base material formula for road pavement design

  5. #5
    Lead Engineer
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    Just a quick response while I am waiting to go to Thanksgiving dinner.

    Generally, if the function "Log" is used in printed literature without any specified other base it is understood to be to the base "10".

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