30.2.2 Ellipse
Contents
Function
\[f = \left(\frac{x-x_c}{a}\right)^2 + \left(\frac{y-y_c}{b}\right)^2 - 1\]
Brief Description
Implicit ellipse equation whose major and minor axes coincide with XY axes.
Sample Curve
Parameters
Number: 4
Names: xc, yc, a, b
Meanings: xc = x center, yc = y center, a = major radius, b = minor radius
Lower Bounds: a > 0.0, b > 0.0
Upper Bounds: none
Derived Parameters
\(Area=\pi ab \;\)
\(e=\sqrt{ 1 - \left(a>b ? \frac{b}{a} : \frac{a}{b}\right)^2 }\)
\[ApproxC=\pi(a+b)\frac{1 + 3\left(\frac{a>b ? (a-b) : (b-a)}{a+b}\right)^2}{10 + \sqrt{4 - 3\left(\frac{a>b ? (a-b) : (b-a)}{a+b}\right)^2}} \]
Script Access
nlf_Ellipse(x,y,xc,yc,a,b)
Function File
FITFUNC\ELLIPSE.FDF
Category
Implicit