func TestDecimal_Hypot(t *testing.T) {
tests := [...]struct {
p, q *decimal.Big
c int32
a string
}{
{decimal.New(1, 0), decimal.New(4, 0), 15, "4.12310562561766"},
{decimal.New(1, 0), decimal.New(4, 0), 10, "4.1231056256"},
{Pi, Pi, 75, "4.442882938158366247015880990060693698614621689375690223085395606956434793099"},
{decimal.New(-12, 0), decimal.New(599, 0), 2, "599.12"},
{decimal.New(1234, 3), decimal.New(987654123, 5), 2, "9876.54"},
{decimal.New(3, 0), decimal.New(4, 0), 0, "5"},
}
var a decimal.Big
for i, v := range tests {
a.SetPrec(v.c)
if got := Hypot(&a, v.p, v.q).String(); got != v.a {
t.Errorf("#%d: wanted %q, got %q", i, v.a, got)
}
}
}
// Hypot sets z to Sqrt(p*p + q*q) and returns z.
func Hypot(z, p, q *decimal.Big) *decimal.Big {
p0 := new(decimal.Big).Set(p)
q0 := new(decimal.Big).Set(q)
if p0.Sign() <= 0 {
p0.Neg(p0)
}
if q0.Sign() <= 0 {
q0.Neg(q0)
}
if p0.Sign() == 0 {
return z.SetMantScale(0, 0)
}
p0.Mul(p0, p0)
q0.Mul(q0, q0)
return Sqrt(z, p0.Add(p0, q0))
}
// Sqrt sets z to the square root of x and returns z.
// The precision of Sqrt is determined by z's Context.
// Sqrt will panic on negative values since decimal.Big cannot
// represent imaginary numbers.
func Sqrt(z, x *decimal.Big) *decimal.Big {
return z.Sqrt(x)
}