fix tgammal: don't set the signgam global

(tgamma must be thread-safe, signgam is for lgamma* functions)

diff --git a/src/math/tgammal.c b/src/math/tgammal.c
index 1b460da51c934deda67bba69811e01f2295ac7cd..86782a967226f0f6fe50a61ae86cf92576eadf8e 100644 (file)
--- 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
@@ -209,9 +205,8 @@ static long double stirf(long double x)
 long double tgammal(long double x)
 {
        long double p, q, z;
-       int i;
+       int i, sign;
 
-       signgam = 1;
        if (isnan(x))
                return NAN;
        if (x == INFINITY)
@@ -220,6 +215,7 @@ long double tgammal(long double x)
                return x - x;
        q = fabsl(x);
        if (q > 13.0) {
+               sign = 1;
                if (q > MAXGAML)
                        goto goverf;
                if (x < 0.0) {
@@ -228,7 +224,7 @@ long double tgammal(long double x)
                                return (x - x) / (x - x);
                        i = p;
                        if ((i & 1) == 0)
-                               signgam = -1;
+                               sign = -1;
                        z = q - p;
                        if (z > 0.5L) {
                                p += 1.0;
@@ -238,13 +234,13 @@ long double tgammal(long double x)
                        z = fabsl(z) * stirf(q);
                        if (z <= PIL/LDBL_MAX) {
 goverf:
-                               return signgam * INFINITY;
+                               return sign * INFINITY;
                        }
                        z = PIL/z;
                } else {
                        z = stirf(x);
                }
-               return signgam * z;
+               return sign * z;
        }
 
        z = 1.0;
@@ -269,8 +265,6 @@ goverf:
        p = __polevll(x, P, 7);
        q = __polevll(x, Q, 8);
        z = z * p / q;
-       if(z < 0)
-               signgam = -1;
        return z;
 
 small:
@@ -279,7 +273,6 @@ small:
        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;