lyapunov {maotai}

Solve Lyapunov Equation

Description

The Lyapunov equation is of form

AX + XA^\top = Q

where A and Q are square matrices of same size. Above form is also known as continuous form. This is a wrapper of armadillo's sylvester function.

Usage

lyapunov(A, Q)

Arguments

A

a (p\times p) matrix as above.

Q

a (p\times p) matrix as above.

Value

a solution matrix X of size (p\times p).

References

Sanderson C, Curtin R (2016). “Armadillo: A Template-Based C++ Library for Linear Algebra.” The Journal of Open Source Software, 1(2), 26.

Eddelbuettel D, Sanderson C (2014). “RcppArmadillo: Accelerating R with High-Performance C++ Linear Algebra.” Computational Statistics and Data Analysis, 71, 1054–1063.

Examples

## simulated example
#  generate square matrices
A = matrix(rnorm(25),nrow=5)
X = matrix(rnorm(25),nrow=5)
Q = A%*%X + X%*%t(A)

#  solve using 'lyapunov' function
solX = lyapunov(A,Q)
## Not run: 
pm1 = "* Experiment with Lyapunov Solver"
pm2 = paste("* Absolute Error  : ",norm(solX-X,"f"),sep="")
pm3 = paste("* Relative Error  : ",norm(solX-X,"f")/norm(X,"f"),sep="")
cat(paste(pm1,"\n",pm2,"\n",pm3,sep=""))

## End(Not run)