Parameters:
(1) a = major diameter in mm
(2) b = minor diameter in mm
roundness index =
= 2 * (major diameter) * (minor diameter) / (((major diameter)^2) + ((minor diameter)^2))
This can be derived from the following relationships:
area of ellipse =
= PI() * (major diameter) * (minor diameter) / 4
circumference of the ellipse =
= PI() * SQRT((((major diameter)^2) + ((minor diameter)^2)) / 2)
circumference of a circle =
= PI() * 2 * (radius)
area of the circle =
= PI() * ((radius)^2)
PI() * 2 * (radius) =
= PI() * SQRT((((major diameter)^2) + ((minor diameter)^2)) / 2)
radius for circle with same circumference =
= (1/2) * SQRT((((major diameter)^2) + ((minor diameter)^2)) / 2)
area of the circle =
= (1/8) * (((major diameter)^2) + ((minor diameter)^2))
