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Creating Field Calculator Expression

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6
01-13-2015 01:06 AM
Deactivated User

Hi, I want to project population from an old census report.....the formula is as follows

population*(1+(growth rate/100))^16

I am trying this expression for calculating from attribute table but ITS NOT WORKING

[POP_B_SEX]*(1+ (4.33 / 100 ))Exp (16 )

Note : [POP_B_SEX] is the only column i am using from attribute table.

1 Solution

Accepted Solutions
Esri Contributor

The formula works for me....

Go in ArcMap to the Geoprocessing menu and click Geoprocessing Results. What is the error message that the Field Calculator returns?

To make the formula more simple:

(1+ (4.33 / 100 ))^16 = 1.97037

Your formula can be rewritten as:

[POP_B_SEX]*1.97037

6 Replies
MVP Emeritus

Exponents aren't ^, they are **

Deactivated User

Yes but you see in the expression i am using "exp()"...wont they work?? and i tried with ** and doesn't work either....i guess there is something wrong with the expression....

Esri Contributor

Exp(16) means e^16 = 2.718282^16 = 8886111

You can simply use the ^ sign as in the formula.

Note: there is a difference between:

[POP_B_SEX]*(1+ (4.33 / 100 ))^16

and

([POP_B_SEX]*(1+ (4.33 / 100 )))^16

Deactivated User

Yeah i tried with ^ already but it doesn't work

Esri Contributor

The formula works for me....

Go in ArcMap to the Geoprocessing menu and click Geoprocessing Results. What is the error message that the Field Calculator returns?

To make the formula more simple:

(1+ (4.33 / 100 ))^16 = 1.97037

Your formula can be rewritten as:

[POP_B_SEX]*1.97037

Deactivated User

Yes it worked i had an extra square bracket..thanks