3 Replies Latest reply on Dec 16, 2015 2:49 PM by peterba1

# Calculation problem

I am trying to bring a calculation that works out the risk of Grass fires.

The original equation is as follows:

=2*EXP(-23.6+5.01*LN(B45+0.001)+0.0281*B42-0.266*SQRT(B43)+0.633*SQRT(B44))

where B45 is Curing (how dry the grass is)

B44 is Wind Speed

B43 is Relative Humitity of the air

and B42 is Temperature.

The calculation I got was:

2*Exp(-23.6+(5.01*Ln(Curing)+.001)+(.0281*Temperature)-.266*Sqrt(Relative Humidity+.633*Sqrt(Wind Speed)))

The results are all wrong.  What is my mistake?

Captain Peter Baxter

• ###### 1. Re: Calculation problem

The order of operations appears to be quite different in your second calc compared to your first.  Should it be like this:

2 *

( Exp

(  -23.6 +

( 5.01 * Ln ( Curing  + 0.001 ) +

( 0.0281 * Temperature ) -

( 0.266 * Sqrt ( Relative Humidity ) +

( 0.633 * Sqrt ( Wind Speed ) )

)

• ###### 2. Re: Calculation problem

Seems like an ideal case for using the Let() statement so that the complex formula stays understandable...

• ###### 3. Re: Calculation problem

Shortly after I asked the question, I found the answer was in misplaced parts of the statement.  It now works very well.  Thanks for your help.