func Psi_n_xg0(n int, x float64, result *Result) error {
if n == 0 {
return Psi_e(x, result)
}
/* Abramowitz + Stegun 6.4.10 */
ln_nf, hzeta := new(Result), new(Result)
stat_hz := Hzeta_e(float64(n+1), x, hzeta)
stat_nf := Lnfact_e(n, ln_nf)
stat_e := Exp_mult_err_e(ln_nf.val, ln_nf.err, hzeta.val, hzeta.err, result)
if gsl.IsEven(n) {
result.val = -result.val
}
return err.Select(stat_e, stat_nf, stat_hz)
}
func Psi_n_e(n int, x float64, result *Result) error {
if n == 0 {
return Psi_e(x, result)
} else if n == 1 {
return Psi_1_e(x, result)
} else if n < 0 || x <= 0.0 {
return DomainError(result)
}
ln_nf, hzeta := new(Result), new(Result)
stat_hz := Hzeta_e(float64(n+1), x, hzeta)
stat_nf := Lnfact_e(n, ln_nf)
stat_e := Exp_mult_err_e(ln_nf.val, ln_nf.err, hzeta.val, hzeta.err, result)
if gsl.IsEven(n) {
result.val = -result.val
}
return err.Select(stat_e, stat_nf, stat_hz)
}
func Hazard_e(x float64, result *Result) error {
if x < 25.0 {
result_ln_erfc := new(Result)
stat_l := Log_erfc_e(x/gsl.M_SQRT2, result_ln_erfc)
lnc := -0.22579135264472743236 /* ln(sqrt(2/pi)) */
arg := lnc - 0.5*x*x - result_ln_erfc.val
stat_e := Exp_e(arg, result)
result.err += 3.0 * (1.0 + math.Abs(x)) * gsl.DBL_EPSILON * math.Abs(result.val)
result.err += math.Abs(result_ln_erfc.err * result.val)
return err.Select(stat_l, stat_e)
} else {
ix2 := 1.0 / (x * x)
corrB := 1.0 - 9.0*ix2*(1.0-11.0*ix2)
corrM := 1.0 - 5.0*ix2*(1.0-7.0*ix2*corrB)
corrT := 1.0 - ix2*(1.0-3.0*ix2*corrM)
result.val = x / corrT
result.err = 2.0 * gsl.DBL_EPSILON * math.Abs(result.val)
return err.SUCCESS
}
return err.FAILURE
}
