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)
}