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package data
import "math"
// 3-component vector
type Vector [3]float64
func (v Vector) X() float64 { return v[0] }
func (v Vector) Y() float64 { return v[1] }
func (v Vector) Z() float64 { return v[2] }
// Returns a*v.
func (v Vector) Mul(a float64) Vector {
return Vector{a * v[0], a * v[1], a * v[2]}
}
// Returns (1/a)*v.
func (v Vector) Div(a float64) Vector {
return v.Mul(1 / a)
}
// Returns a+b.
func (a Vector) Add(b Vector) Vector {
return Vector{a[0] + b[0], a[1] + b[1], a[2] + b[2]}
}
// Returns a+s*b.
func (a Vector) MAdd(s float64, b Vector) Vector {
return Vector{a[0] + s*b[0], a[1] + s*b[1], a[2] + s*b[2]}
}
// Returns a-b.
func (a Vector) Sub(b Vector) Vector {
return Vector{a[0] - b[0], a[1] - b[1], a[2] - b[2]}
}
// Returns the norm of v.
func (v Vector) Len() float64 {
len2 := v.Dot(v)
return math.Sqrt(len2)
}
// Returns the dot (inner) product a.b.
func (a Vector) Dot(b Vector) float64 {
return a[0]*b[0] + a[1]*b[1] + a[2]*b[2]
}
// Returns the cross (vector) product a x b
// in a right-handed coordinate system.
func (a Vector) Cross(b Vector) Vector {
x := a[1]*b[2] - a[2]*b[1]
y := a[2]*b[0] - a[0]*b[2]
z := a[0]*b[1] - a[1]*b[0]
return Vector{x, y, z}
}
const (
X = 0
Y = 1
Z = 2
)
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