Definition of the Eccentricity - Axis Based

The eccentricity of an ellipse is basically an indicator of its shape, or how "oval" it is. The value ranges from 0 to 1 and is a ratio of 'c' to 'a'. The value of 'c' is the distance between the center vertex and one focal point.

• The eccentricity value approaches zero as the shape of the ellipse approaches a circle.
  • See Figure 1 (Eccentricity of 0.44)

   

• The eccentricity value approaches one as the shape of the ellipse approaches a line
  • See Figure 2 (Eccentricity of 0.96)

Figure 1		Figure 2