compan

Companion matrix

Syntax

A = compan(u)


Description

A = compan(u) returns the corresponding companion matrix whose first row is -u(2:n)/u(1), where u is a vector of polynomial coefficients. The eigenvalues of compan(u) are the roots of the polynomial.

Examples

Companion Matrix for Polynomial

Compute the companion matrix corresponding to the polynomial $$(x-1)(x-2)(x+3)=x^3-7x+6$$.

u = [1 0 -7 6];
A = compan(u)

A = 3×3

     0     7    -6
     1     0     0
     0     1     0

The eigenvalues of A are the polynomial roots.

eig(A)

ans = 3×1

   -3.0000
    2.0000
    1.0000

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The compan function fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray (Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced before R2006a