Circumference of circle is inaccurate

[littlepear]

Why would the circumference of a circle not equal 2πr?
Should be 27342.85714285714, but listing the circle shows 27331.856086.

 

CIRCLE    Layer: "0"
                  Space: Model space
                  Handle = 48a90
                  center point, X=-6233.093303  Y=32514.666153  Z= 0.000000
                  radius 4350.000000
                  circumference 27331.856086

[CyberAngel]

My guess would be that AutoCAD is using a less precise value of Pi. When I use 3.14, I get a circumference of 27318.

[SEANT]

22/7 is only an approximation for PI.

Edited August 17, 2020 by SEANT

[ammobake]

It appears the value of PI used by Autocad goes down to at least 11 or 12 decimal places - to get the number you posted above from atuocad.

Default Autocad then rounds to the nearest 1 millionth of a unit.

For most applications this would be enough.

 

I can understand why some vendors would want more precision in very specific scenarios.  In those instances it would be better to do the calculations outside of CAD and insert those standalone calculations manually.

 

There may also be an app on the autodesk app store that can do this for you.

(no idea).

 

-ChriS

 

[BIGAL]

Using windows calculator pi=3.1415926535897932384626433832795

 

(rtos pi 2 16) "3.141592653589793" this appears to be max value.