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spatial/r{2,3}: add Norm and Norm2

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This commit is contained in:
Sebastien Binet
2020-04-01 11:26:45 +02:00
committed by GitHub
parent def9e57adc
commit 962425fcd9
4 changed files with 116 additions and 1 deletions
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14
spatial/r2/vector.go
View File

@@ -4,6 +4,8 @@
package r2
import "math"
// Vec is a 2D vector.
type Vec struct {
X, Y float64
@@ -40,6 +42,18 @@ func (p Vec) Cross(q Vec) float64 {
return p.X*q.Y - p.Y*q.X
}
// Norm returns the Euclidean norm of p
// |p| = sqrt(p_x^2 + p_y^2).
func Norm(p Vec) float64 {
return math.Hypot(p.X, p.Y)
}
// Norm returns the Euclidean squared norm of p
// |p|^2 = p_x^2 + p_y^2.
func Norm2(p Vec) float64 {
return p.X*p.X + p.Y*p.Y
}
// Box is a 2D bounding box.
type Box struct {
Min, Max Vec

48
spatial/r2/vector_test.go
View File

@@ -4,7 +4,10 @@
package r2
import "testing"
import (
"math"
"testing"
)
func TestAdd(t *testing.T) {
for _, test := range []struct {
@@ -135,3 +138,46 @@ func TestCross(t *testing.T) {
})
}
}
func TestNorm(t *testing.T) {
for _, test := range []struct {
v Vec
want float64
}{
{Vec{0, 0}, 0},
{Vec{0, 1}, 1},
{Vec{1, 1}, math.Sqrt2},
{Vec{1, 2}, math.Sqrt(5)},
{Vec{3, -4}, 5},
{Vec{1, 1e-16}, 1},
{Vec{4.3145006366056343748277397783556100978621924913975e-196, 4.3145006366056343748277397783556100978621924913975e-196}, 6.101625315155041e-196},
} {
t.Run("", func(t *testing.T) {
if got, want := Norm(test.v), test.want; got != want {
t.Fatalf("|%v| = %v, want %v", test.v, got, want)
}
})
}
}
func TestNorm2(t *testing.T) {
for _, test := range []struct {
v Vec
want float64
}{
{Vec{0, 0}, 0},
{Vec{0, 1}, 1},
{Vec{1, 1}, 2},
{Vec{1, 2}, 5},
{Vec{3, -4}, 25},
{Vec{1, 1e-16}, 1},
// This will underflow and return zero.
{Vec{4.3145006366056343748277397783556100978621924913975e-196, 4.3145006366056343748277397783556100978621924913975e-196}, 0},
} {
t.Run("", func(t *testing.T) {
if got, want := Norm2(test.v), test.want; got != want {
t.Fatalf("|%v|^2 = %v, want %v", test.v, got, want)
}
})
}
}

14
spatial/r3/vector.go
View File

@@ -4,6 +4,8 @@
package r3
import "math"
// Vec is a 3D vector.
type Vec struct {
X, Y, Z float64
@@ -47,6 +49,18 @@ func (p Vec) Cross(q Vec) Vec {
}
}
// Norm returns the Euclidean norm of p
// |p| = sqrt(p_x^2 + p_y^2 + p_z^2).
func Norm(p Vec) float64 {
return math.Hypot(p.X, math.Hypot(p.Y, p.Z))
}
// Norm returns the Euclidean squared norm of p
// |p|^2 = p_x^2 + p_y^2 + p_z^2.
func Norm2(p Vec) float64 {
return p.X*p.X + p.Y*p.Y + p.Z*p.Z
}
// Box is a 3D bounding box.
type Box struct {
Min, Max Vec

41
spatial/r3/vector_test.go
View File

@@ -135,3 +135,44 @@ func TestCross(t *testing.T) {
})
}
}
func TestNorm(t *testing.T) {
for _, test := range []struct {
v Vec
want float64
}{
{Vec{0, 0, 0}, 0},
{Vec{0, 1, 0}, 1},
{Vec{3, -4, 12}, 13},
{Vec{1, 1e-16, 1e-32}, 1},
{Vec{-0, 4.3145006366056343748277397783556100978621924913975e-196, 4.3145006366056343748277397783556100978621924913975e-196}, 6.101625315155041e-196},
} {
t.Run("", func(t *testing.T) {
if got, want := Norm(test.v), test.want; got != want {
t.Fatalf("|%v| = %v, want %v", test.v, got, want)
}
})
}
}
func TestNorm2(t *testing.T) {
for _, test := range []struct {
v Vec
want float64
}{
{Vec{0, 0, 0}, 0},
{Vec{0, 1, 0}, 1},
{Vec{1, 1, 1}, 3},
{Vec{1, 2, 3}, 14},
{Vec{3, -4, 12}, 169},
{Vec{1, 1e-16, 1e-32}, 1},
// This will underflow and return zero.
{Vec{-0, 4.3145006366056343748277397783556100978621924913975e-196, 4.3145006366056343748277397783556100978621924913975e-196}, 0},
} {
t.Run("", func(t *testing.T) {
if got, want := Norm2(test.v), test.want; got != want {
t.Fatalf("|%v|^2 = %v, want %v", test.v, got, want)
}
})
}
}