light polylines and curvature in relation to the value associated with the code dxf 42

[Giuseppe Beatrice]

Hello, everyone.
I have a question... theoretical that I asked myself questioning entities of type lwpolyline also constituted by circle arches.
In this case, as is logical, the value associated with the code dxf 42 (curvatura) corresponding to each starting point of a circle section assumes a real value (positive or negative) different from 0.
what I couldn't understand is exactly what corresponds to that value: in fact it does not represent neither the radius of the circle arc, nor its reverse, nor the value of the trigonometric tangent at the arc that point... So how the hell does autocad calculate it?
I understand that the problem that I pose may seem purely theoretical, but understanding the genesis of that value could, for example, allow the creation of a light polyline with tangent circle arches to the initial segments, so I think it is worth comparing us.
thanks to everyone as usual.

 

[confutatis]

the value 42 is the ratio between the arrow and the distance between the split bending points 2.

c=f/d*0.5

takes negative value when the curve goes right, starting from the initial point of the polylinea, positive value when it goes left.

 

[Joseph]

to complete the information, here is an image.

If you want more detailed information, go here:http://www.afralisp.net/archive/lisp/bulges1.htm

 

[Giuseppe Beatrice]

Once again... Thank you!