From: Jens Vollinga <vollinga@thep.physik.uni-mainz.de>
Date: Thu, 18 Mar 2004 17:03:24 +0000 (+0000)
Subject: S(0,p,x) now evaluates numerically
X-Git-Tag: release_1-2-0~2
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=commitdiff_plain;h=bb2430ce924b2bb49bc537a63aeddfc8326b9188;p=ginac.git

S(0,p,x) now evaluates numerically
---

diff --git a/ginac/inifcns_nstdsums.cpp b/ginac/inifcns_nstdsums.cpp
index 3b7fc556..ec9586ed 100644
--- a/ginac/inifcns_nstdsums.cpp
+++ b/ginac/inifcns_nstdsums.cpp
@@ -939,9 +939,8 @@ numeric S_num(int n, int p, const numeric& x)
 	else if (!x.imag().is_rational())
 		prec = cln::float_format(cln::the<cln::cl_F>(cln::imagpart(value)));
 
-
 	// [Kol] (5.3)
-	if (cln::realpart(value) < -0.5) {
+	if ((cln::realpart(value) < -0.5) || (n == 0)) {
 
 		cln::cl_N result = cln::expt(cln::cl_I(-1),p) * cln::expt(cln::log(value),n)
 		                   * cln::expt(cln::log(1-value),p) / cln::factorial(n) / cln::factorial(p);
@@ -1029,6 +1028,10 @@ static ex S_eval(const ex& n, const ex& p, const ex& x)
 			return S_num(ex_to<numeric>(n).to_int(), ex_to<numeric>(p).to_int(), ex_to<numeric>(x));
 		}
 	}
+	if (n.is_zero()) {
+		// [Kol] (5.3)
+		return pow(-log(1-x), p) / factorial(p);
+	}
 	return S(n, p, x).hold();
 }