X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fmath%2Ftgammal.c;h=5c1a02a6399692ca60037f346e4e1be1f8163f19;hp=1b460da51c934deda67bba69811e01f2295ac7cd;hb=HEAD;hpb=634c3a63027aa4a693b64fae0e2f6e1635558e93

diff --git a/src/math/tgammal.c b/src/math/tgammal.c
index 1b460da5..5c1a02a6 100644
--- a/src/math/tgammal.c
+++ b/src/math/tgammal.c
@@ -21,7 +21,6 @@
  * SYNOPSIS:
  *
  * long double x, y, tgammal();
- * extern int signgam;
  *
  * y = tgammal( x );
  *
@@ -29,10 +28,7 @@
  * DESCRIPTION:
  *
  * Returns gamma function of the argument.  The result is
- * correctly signed, and the sign (+1 or -1) is also
- * returned in a global (extern) variable named signgam.
- * This variable is also filled in by the logarithmic gamma
- * function lgamma().
+ * correctly signed.
  *
  * Arguments |x| <= 13 are reduced by recurrence and the function
  * approximated by a rational function of degree 7/8 in the
@@ -209,42 +205,36 @@ static long double stirf(long double x)
 long double tgammal(long double x)
 {
 	long double p, q, z;
-	int i;
 
-	signgam = 1;
-	if (isnan(x))
-		return NAN;
-	if (x == INFINITY)
-		return INFINITY;
-	if (x == -INFINITY)
-		return x - x;
+	if (!isfinite(x))
+		return x + INFINITY;
+
 	q = fabsl(x);
 	if (q > 13.0) {
-		if (q > MAXGAML)
-			goto goverf;
 		if (x < 0.0) {
 			p = floorl(q);
-			if (p == q)
-				return (x - x) / (x - x);
-			i = p;
-			if ((i & 1) == 0)
-				signgam = -1;
 			z = q - p;
-			if (z > 0.5L) {
-				p += 1.0;
-				z = q - p;
-			}
-			z = q * sinl(PIL * z);
-			z = fabsl(z) * stirf(q);
-			if (z <= PIL/LDBL_MAX) {
-goverf:
-				return signgam * INFINITY;
+			if (z == 0)
+				return 0 / z;
+			if (q > MAXGAML) {
+				z = 0;
+			} else {
+				if (z > 0.5) {
+					p += 1.0;
+					z = q - p;
+				}
+				z = q * sinl(PIL * z);
+				z = fabsl(z) * stirf(q);
+				z = PIL/z;
 			}
-			z = PIL/z;
+			if (0.5 * p == floorl(q * 0.5))
+				z = -z;
+		} else if (x > MAXGAML) {
+			z = x * 0x1p16383L;
 		} else {
 			z = stirf(x);
 		}
-		return signgam * z;
+		return z;
 	}
 
 	z = 1.0;
@@ -269,17 +259,15 @@ goverf:
 	p = __polevll(x, P, 7);
 	q = __polevll(x, Q, 8);
 	z = z * p / q;
-	if(z < 0)
-		signgam = -1;
 	return z;
 
 small:
-	if (x == 0.0)
-		return (x - x) / (x - x);
+	/* z==1 if x was originally +-0 */
+	if (x == 0 && z != 1)
+		return x / x;
 	if (x < 0.0) {
 		x = -x;
 		q = z / (x * __polevll(x, SN, 8));
-		signgam = -1;
 	} else
 		q = z / (x * __polevll(x, S, 8));
 	return q;