blob: cd815fc1b1335ee6d0a6d93cd449d7a06dcda389 [file] [log] [blame]
// Copyright ©2020 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 distmat_test
import (
"fmt"
"golang.org/x/exp/rand"
"gonum.org/v1/gonum/mat"
"gonum.org/v1/gonum/stat/distmat"
)
// ExampleUnitVector uses the UnitVector distribution to take
// a random walk in n-space. At the end it computes how far
// from the origin the walk finished.
func ExampleUnitVector() {
src := rand.NewSource(1)
rnd := rand.New(src)
dist := distmat.NewUnitVector(src)
// Draw a random dimension for the space to walk through.
nDim := 1 + rnd.Intn(100)
// Vectors to hold the current position and next step.
position := mat.NewVecDense(nDim, nil)
step := mat.NewVecDense(nDim, nil)
// Draw a random number of steps to take.
nSteps := 1 + rnd.Intn(100)
for i := 0; i < nSteps; i++ {
// Draw a random step and update the position.
dist.UnitVecTo(step)
position.AddVec(position, step)
}
// Finally compute distance from the origin.
distance := mat.Norm(position, 2)
fmt.Printf("took %d steps in %d-space, walked %1.1f in total", nSteps, nDim, distance)
// Output:
// took 22 steps in 52-space, walked 5.3 in total
}