Creating Field Calculator Expression

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01-13-2015 01:06 AM
WahajHabib
New Contributor

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.

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Pieter_Geertvan_den_Beukel
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

View solution in original post

6 Replies
DanPatterson_Retired
MVP Esteemed Contributor

Exponents aren't ^, they are **

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WahajHabib
New Contributor

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....

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Pieter_Geertvan_den_Beukel
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

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WahajHabib
New Contributor

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

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Pieter_Geertvan_den_Beukel
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

View solution in original post

WahajHabib
New Contributor

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

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