# conicMatrix: Matrix representing a conic In conics: Plot Conics

## Description

Build a symmetric matrix representing a quadratic polynomial in two variables.

## Usage

 `1` ``` conicMatrix(v) ```

## Arguments

 `v` (`vector`) a 6-length vector containing the coefficients of a quadratic polynomial.

## Details

The `v` argument is a 6-length vector containing the coefficients of a quadratic polynomial of the form:

 `1` ``` P(x_1,x_2) = v_1 x_1^2 + v_2 x_1 x_2 + v_3 x_2^2 + v_4 x_1 + v_5 x_2 + v_6 ```

 `1` ``` Q(x_1,x_2,x_3) = v_1 x_1^2 + v_2 x_1 x_2 + v_3 x_2^2 + v_4 x_1 x_3 + v_5 x_2 x_3 + v_6 x_3^2 ```

## Value

Return the symmetric 3x3 matrix representing the associated quadratic form.

## Author(s)

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

`conicAsymptotes`, `conicAxes`, `conicCenter`, `conicPlot`
 ```1 2 3``` ```# 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) conicMatrix(v) ```