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// Copyright ©2018 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mat_test
import (
"fmt"
"log"
"gonum.org/v1/gonum/mat"
)
func ExampleEigenSym() {
a := mat.NewSymDense(2, []float64{
7, 0.5,
0.5, 1,
})
fmt.Printf("A = %v\n\n", mat.Formatted(a, mat.Prefix(" ")))
var eigsym mat.EigenSym
ok := eigsym.Factorize(a, true)
if !ok {
log.Fatal("Symmetric eigendecomposition failed")
}
fmt.Printf("Eigenvalues of A:\n%1.3f\n\n", eigsym.Values(nil))
var ev mat.Dense
eigsym.VectorsTo(&ev)
fmt.Printf("Eigenvectors of A:\n%1.3f\n\n", mat.Formatted(&ev))
// Output:
// A = ⎡ 7 0.5⎤
// ⎣0.5 1⎦
//
// Eigenvalues of A:
// [0.959 7.041]
//
// Eigenvectors of A:
// ⎡ 0.082 -0.997⎤
// ⎣-0.997 -0.082⎦
//
}
func ExampleEigen() {
a := mat.NewDense(2, 2, []float64{
1, -1,
1, 1,
})
fmt.Printf("A = %v\n\n", mat.Formatted(a, mat.Prefix(" ")))
var eig mat.Eigen
ok := eig.Factorize(a, mat.EigenLeft)
if !ok {
log.Fatal("Eigendecomposition failed")
}
fmt.Printf("Eigenvalues of A:\n%v\n", eig.Values(nil))
// Output:
// A = ⎡ 1 -1⎤
// ⎣ 1 1⎦
//
// Eigenvalues of A:
// [(1+1i) (1-1i)]
}
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