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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

collapse all

Compute the companion matrix corresponding to the polynomial (x-1)(x-2)(x+3)=x3-7x+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™.

See Also

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Introduced before R2006a