R-alpha: Buglet & patch in dbinom.c (0.50 - PreR 7)

[Martin Maechler]

dbinom(k, n, prob = 0) # or  prob=1   would not work;

The following patch makes it work (in  $RHOME/src/math/ ) :

--- dbinom.c~	Sun Nov 24 23:43:10 1996
+++ dbinom.c	Tue Apr 15 23:31:46 1997
@@ -23,9 +23,13 @@
 {
 	x = floor(x + 0.5);
 	n = floor(n + 0.5);
-	if (n <= 0.0 || p <= 0.0 || p >= 1.0)
+	if (n <= 0.0 || p < 0.0 || p > 1.0)
 		DOMAIN_ERROR;
 	if (x < 0.0 || x > n)
 		return 0.0;
+	if (p == 0.0)
+	        return (x == 0) ? 1.0 : 0.0;
+	if (p == 1.0)
+	        return (x == n) ? 1.0 : 0.0;
 	return exp(lfastchoose(n, x) + log(p) * x + (n - x) * log(1.0 - p));
 }
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