// j1(x) = 1/sqrt(pi) * (P(1,x)*cc - Q(1,x)*ss) / sqrt(x)
		// y1(x) = 1/sqrt(pi) * (P(1,x)*ss + Q(1,x)*cc) / sqrt(x)

		var z float64
		if x > Two129 {
			z = (1 / SqrtPi) * cc / Sqrt(x)
		} else {
			u := pone(x)
			v := qone(x)
			z = (1 / SqrtPi) * (u*cc - v*ss) / Sqrt(x)
		}
		if sign {
			return -z
		}
		return z
	}
	if x < TwoM27 { // |x|<2**-27
		return 0.5 * x // inexact if x!=0 necessary

	Sqrt2   = 1.41421356237309504880168872420969807856967187537694807317667974 // https://oeis.org/A002193
	SqrtE   = 1.64872127070012814684865078781416357165377610071014801157507931 // https://oeis.org/A019774
	SqrtPi  = 1.77245385090551602729816748334114518279754945612238712821380779 // https://oeis.org/A002161
	SqrtPhi = 1.27201964951406896425242246173749149171560804184009624861664038 // https://oeis.org/A139339

		// y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x)

		var z float64
		if x > Two129 { // |x| > ~6.8056e+38
			z = (1 / SqrtPi) * cc / Sqrt(x)
		} else {
			u := pzero(x)
			v := qzero(x)
			z = (1 / SqrtPi) * (u*cc - v*ss) / Sqrt(x)
		}
		return z // |x| >= 2.0
	}
	if x < TwoM13 { // |x| < ~1.2207e-4
		if x < TwoM27 {
			return 1 // |x| < ~7.4506e-9
		}

			var temp float64
			switch s, c := Sincos(x); n & 3 {
			case 0:
				temp = c + s
			case 1:
				temp = -c + s
			case 2:
				temp = -c - s
			case 3:
				temp = c - s
			}
			b = (1 / SqrtPi) * temp / Sqrt(x)
		} else {
			b = J1(x)
			for i, a := 1, J0(x); i < n; i++ {
				a, b = b, b*(float64(i+i)/x)-a // avoid underflow
			}
		}
	} else {
		if x < TwoM29 { // x < 2**-29

		{"Sinh", Func, 0},
		{"SmallestNonzeroFloat32", Const, 0},
		{"SmallestNonzeroFloat64", Const, 0},
		{"Sqrt", Func, 0},
		{"Sqrt2", Const, 0},
		{"SqrtE", Const, 0},
		{"SqrtPhi", Const, 0},
		{"SqrtPi", Const, 0},
		{"Tan", Func, 0},
		{"Tanh", Func, 0},
		{"Trunc", Func, 0},
		{"Y0", Func, 0},
		{"Y1", Func, 0},
		{"Yn", Func, 0},
	},
	"math/big": {
		{"(*Float).Abs", Method, 5},

pkg math, const SmallestNonzeroFloat64 ideal-float
pkg math, const Sqrt2 ideal-float
pkg math, const SqrtE ideal-float
pkg math, const SqrtPhi ideal-float
pkg math, const SqrtPi ideal-float
pkg math, func Abs(float64) float64
pkg math, func Acos(float64) float64
pkg math, func Acosh(float64) float64
pkg math, func Asin(float64) float64
pkg math, func Asinh(float64) float64

pkg math, const SqrtPhi = 1.27202  // 63600982475703448212621123086874574585780402092004812430832019/50000000000000000000000000000000000000000000000000000000000000
pkg math, const SqrtPi = 1.77245  // 177245385090551602729816748334114518279754945612238712821380779/100000000000000000000000000000000000000000000000000000000000000
pkg math/big, const MaxBase = 36
pkg math/big, method (*Int) MarshalJSON() ([]uint8, error)