conicAxes: Axes of a conic

In conics: Plot Conics

Description

Find the symmetry axes of a conic.

Usage

	conicAxes(x) 

Arguments

x	a 6-length vector or a symmetric 3x3 matrix

Details

The conicAxes function calculates the coordinates of the symmetry axes of a conic specified by its coefficients or by its symmetric matrix.

The direction vectors of the axes are the eigenvectors of the top-left 2x2 submatrix of the matrix representing the conic.

Value

A 2x2 matrix whose columns are the direction vectors of the axes. In order to find the coordinates of the center, see the function conicCenter.

Author(s)

Bernard Desgraupes
[e-mail]
University of Paris Ouest - Nanterre
Lab Modal'X (EA 3454)

See Also

conicAsymptotes, conicCenter, conicMatrix, conicPlot

Examples

# Ellipse
# Equation: 2*x_1^2 + 2*x_1*x_2 + 2*x_2^2 - 20*x_1 - 28*x_2 + 10 = 0
v <- c(2,2,2,-20,-28,10)
conicAxes(v)

# Hyperbola
# Equation: 2*x_1^2 + 2*x_1*x_2 - 2*x_2^2 - 20*x_1 + 20*x_2 + 10 = 0
v <- c(2,2,-2,-20,20,10)
conicAxes(v)

conics documentation built on May 2, 2019, 4:15 a.m.