package triangle
import "fmt"
func ExampleKindFromSides() {
	e := KindFromSides(1, 2, 3)
	fmt.Println(e)
	// Output: Sca
}

/*
Package triangle determines if a triangle is equilateral, isosceles or scalene.
*/
package triangle
import "math"
// Kind is a the type of the triangle
type Kind int
// Triangle types
const (
	NaT Kind = iota // not a triangle
	Equ             // equilateral
	Iso             // isosceles
	Sca             // scalene
)
// KindFromSides reads the length of each side of a triangle and returns its Kind.
func KindFromSides(a, b, c float64) (k Kind) {
	// XXX check for degenerate
	switch {
	case a <= 0 || b <= 0 || c <= 0:
		return NaT
	case a+b < c || a+c < b || b+c < a:
		// Because of < instead of <= degenerate is accepted as a triangle
		return NaT
	case math.IsNaN(a) || math.IsNaN(b) || math.IsNaN(c):
		return NaT
	case math.IsInf(a, 0) || math.IsInf(b, 0) || math.IsInf(c, 0):
		return NaT
	case a == b && a == c:
		return Equ
	case a == b || b == c || a == c:
		// only two sides can be equal, as we checked for all 3 side in the previous case
		return Iso
	default:
		return Sca
	}
}