Existing Tree Tool

[Ozzie]

Hi all
We in OZ operate from an Australian Standard - AS 4970 Protection of Trees on Developments Site
 

It has a formula to calculate Structural Root Zone which is when you measure across the base of the tree
The standard says ...
An indicative SRZ radius can be determined from the trunk diameter measured immediately above the root buttress using the following formula.
This is called Diameter at Buttress (DAB)

SRZ radius = (D × 50) to the power of 0.42 × 0.64

Where the D is in metres
I have built an app to collect data on site but we use millimetres not metres
Does anyone know how to convert that formula so that for D is in mm instead of metres

I thought about it and came up with ...
If DAB is 500 mm
(500 * .05) ^ .42 * 640 and that works
I checked it with DAB = 200, 300 and 400 and they all work also
But is my formula correct?

[Pat Stanford]

From a strictly algebraic viewpoint,  1 Meter = 1000 mm, so if you enter D in MM you need to divide it by 1000 to get meters.   So the following should get you the SRZ in meters while allowing you to enter D in mm.

 

SRZ radius = ((D / 1000) × 50) to the power of 0.42 × 0.64  

 

If you want the SRZ to be reported in mm, as well as entering D in mm then you will need:

 

SRZ radius = (((D / 1000) × 50) to the power of 0.42 × 0.64) * 1000