//         We use the following function to approximate y0,
//              y0(x) = U(z)/V(z) + (2/pi)*(j0(x)*ln(x)), z= x**2
//         where
//              U(z) = u00 + u01*z + ... + u06*z**6
//              V(z) = 1  + v01*z + ... + v04*z**4
//         with absolute approximation error bounded by 2**-72.
//         Note: For tiny x, U/V = u0 and j0(x)~1, hence

	const (
		TwoM54 = 1.0 / (1 << 54)             // 2**-54 0x3c90000000000000
		Two129 = 1 << 129                    // 2**129 0x4800000000000000
		U00    = -1.96057090646238940668e-01 // 0xBFC91866143CBC8A
		U01    = 5.04438716639811282616e-02  // 0x3FA9D3C776292CD1
		U02    = -1.91256895875763547298e-03 // 0xBF5F55E54844F50F
		U03    = 2.35252600561610495928e-05  // 0x3EF8AB038FA6B88E