func main() {
m := len(yGiven)
n := degree + 1
y := matrix.MakeDenseMatrix(yGiven, m, 1)
x := matrix.Zeros(m, n)
for i := 0; i < m; i++ {
ip := float64(1)
for j := 0; j < n; j++ {
x.Set(i, j, ip)
ip *= xGiven[i]
}
}
q, r := x.QR()
qty, err := q.Transpose().Times(y)
if err != nil {
fmt.Println(err)
return
}
c := make([]float64, n)
for i := n - 1; i >= 0; i-- {
c[i] = qty.Get(i, 0)
for j := i + 1; j < n; j++ {
c[i] -= c[j] * r.Get(i, j)
}
c[i] /= r.Get(i, i)
}
fmt.Println(c)
}
func givens() (x, y *matrix.DenseMatrix) {
height := []float64{1.47, 1.50, 1.52, 1.55, 1.57, 1.60, 1.63,
1.65, 1.68, 1.70, 1.73, 1.75, 1.78, 1.80, 1.83}
weight := []float64{52.21, 53.12, 54.48, 55.84, 57.20, 58.57, 59.93,
61.29, 63.11, 64.47, 66.28, 68.10, 69.92, 72.19, 74.46}
m := len(height)
n := 3
y = matrix.MakeDenseMatrix(weight, m, 1)
x = matrix.Zeros(m, n)
for i := 0; i < m; i++ {
ip := float64(1)
for j := 0; j < n; j++ {
x.Set(i, j, ip)
ip *= height[i]
}
}
return
}
func main() {
// Beacon positions
var beaconA = newPos(0.0, 0.0)
var beaconB = newPos(0.0, 2000.0)
var beaconC = newPos(3000.0, 1000.0)
// First state
var x0 matrix.Matrix = matrix.MakeDenseMatrix([]float64{200, 0, 200, 0}, 4, 1)
var P0 matrix.Matrix = matrix.Diagonal([]float64{10000, 100, 10000, 100})
fmt.Printf(">init:\n")
fmt.Printf("x0:\n%v\n\n", x0)
fmt.Printf("P0:\n%v\n\n", P0)
// x(k+1) = Ax + Bu + Ww
var W matrix.Matrix = matrix.MakeDenseMatrix([]float64{
0.0, 0.0,
1.0, 0.0,
0.0, 0.0,
0.0, 1.0}, 4, 2)
fmt.Printf("> noise\n")
fmt.Printf("W:\n%v\n\n", W)
// Design
var d = 0.01 * 0.01
var Q matrix.Matrix = matrix.Diagonal([]float64{d, d})
var R matrix.Matrix = matrix.Diagonal([]float64{d, d, d})
fmt.Printf(">Design\n")
fmt.Printf("Q:\n%v\n\n", Q)
fmt.Printf("R:\n%v\n\n", R)
// Init filter
var u matrix.Matrix = matrix.MakeDenseMatrix([]float64{0, 0}, 2, 1)
var y matrix.Matrix = matrix.MakeDenseMatrix([]float64{1000, 1000, 3000}, 3, 1)
// df(x,u)/dx
dfdx := func(x, u matrix.Matrix) matrix.Matrix {
// The process is independent of possition, df/dx = A
T := 1.0
A := matrix.MakeDenseMatrix([]float64{
1.0, T, 0.0, 0.0,
0.0, 1.0, 0.0, 0.0,
0.0, 0.0, 1.0, T,
0.0, 0.0, 0.0, 1.0}, 4, 4)
return A
}
// Estimated movement of robot given state x
f := func(x, u matrix.Matrix) matrix.Matrix {
// x(k+1) = Ax + Bu
var A = dfdx(x, u)
return matrix.Product(A, x)
// Commented out: take motor gain in to account:
/*
var B matrix.Matrix = matrix.MakeDenseMatrix([]float64{
0.0, 0.0,
0.0, 0.0,
0.0, 0.0,
0.0, 0.0}, 4, 2)
return matrix.Sum( matrix.Product(A, x), matrix.Product(B, u))
*/
}
// dh(x,u)/dx
dhdx := func(x matrix.Matrix) matrix.Matrix {
// Linearisation of H around x(k)
robot := newPos(x.Get(0, 0), x.Get(2, 0))
denA := math.Sqrt(math.Pow(robot.X-beaconA.X, 2.0) + math.Pow(robot.Y-beaconA.Y, 2.0))
denB := math.Sqrt(math.Pow(robot.X-beaconB.X, 2.0) + math.Pow(robot.Y-beaconB.Y, 2.0))
denC := math.Sqrt(math.Pow(robot.X-beaconC.X, 2.0) + math.Pow(robot.Y-beaconC.Y, 2.0))
H := matrix.MakeDenseMatrix([]float64{
(robot.X - beaconA.X) / denA, 0.0, (robot.Y - beaconA.Y) / denA, 0.0,
(robot.X - beaconB.X) / denB, 0.0, (robot.Y - beaconB.Y) / denB, 0.0,
(robot.X - beaconC.X) / denC, 0.0, (robot.Y - beaconC.Y) / denC, 0.0}, 3, 4)
return H
}
// Measure estimate given state x
h := func(x matrix.Matrix) matrix.Matrix {
var robot = newPos(x.Get(0, 0), x.Get(2, 0))
var y matrix.Matrix = matrix.MakeDenseMatrix([]float64{
math.Sqrt(math.Pow(robot.X-beaconA.X, 2.0) + math.Pow(robot.Y-beaconA.Y, 2.0)),
math.Sqrt(math.Pow(robot.X-beaconB.X, 2.0) + math.Pow(robot.Y-beaconB.Y, 2.0)),
math.Sqrt(math.Pow(robot.X-beaconC.X, 2.0) + math.Pow(robot.Y-beaconC.Y, 2.0))}, 3, 1)
return y
}
// State variable
var x matrix.Matrix
// Initalize kalman filter
var filter = extkalman.ExtendedKalman(W, R, Q, x0, P0, f, dfdx, h, dhdx)
// Run filter
fmt.Printf("Running:\n")
for {
x = filter.Step(y, u)
fmt.Printf("x:\n%v\n\n", x)
}
}
