# Thread: Help w/simple excel log formula

1. ## 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

2. =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. 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

4. ## The Following User Says Thank You to sdckapr For This Useful Post:

mojave1 (2012-05-31)

5. 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?

6. 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/y² it is (x/y)²

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

Steve

7. ## The Following User Says Thank You to sdckapr For This Useful Post:

mojave1 (2012-06-02)

8. my sentiments exactly, thatnks for the assistance Steve....

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