return complex(math.Inf(1), math.NaN())
		}
	case im == 0 && math.IsNaN(re):
		return complex(math.NaN(), im)
	}
	s, c := math.Sincos(imag(x))
	sh, ch := sinhcosh(real(x))
	return complex(c*ch, s*sh)
}

// calculate sinh and cosh.
func sinhcosh(x float64) (sh, ch float64) {
	if math.Abs(x) <= 0.5 {
		return math.Sinh(x), math.Cosh(x)
	}
	e := math.Exp(x)
	ei := 0.5 / e
	e *= 0.5

	for i := 0; i < len(trigHuge); i++ {
		f1, g1 := sinHuge[i], cosHuge[i]
		f2, g2 := Sincos(trigHuge[i])
		if !close(f1, f2) || !close(g1, g2) {
			t.Errorf("Sincos(%g) = %g, %g, want %g, %g", trigHuge[i], f2, g2, f1, g1)
		}
		f3, g3 := Sincos(-trigHuge[i])
		if !close(-f1, f3) || !close(g1, g3) {
			t.Errorf("Sincos(%g) = %g, %g, want %g, %g", -trigHuge[i], f3, g3, -f1, g1)
		}
	}
}

		return complex(0, 0)
	}
	r := math.Pow(modulus, real(y))
	arg := Phase(x)
	theta := real(y) * arg
	if imag(y) != 0 {
		r *= math.Exp(-imag(y) * arg)
		theta += imag(y) * math.Log(modulus)
	}
	s, c := math.Sincos(theta)
	return complex(r*c, r*s)