fix potentially wrong-sign zero in cproj functions at infinity

[musl] / src / math / atan.c

diff --git a/src/math/atan.c b/src/math/atan.c
index 3c9a59f..63b0ab2 100644 (file)
--- a/src/math/atan.c
+++ b/src/math/atan.c
@@ -62,7 +62,7 @@ static const double aT[] = {
 
 double atan(double x)
 {
-       double w,s1,s2,z;
+       double_t w,s1,s2,z;
        uint32_t ix,sign;
        int id;
 
@@ -77,8 +77,9 @@ double atan(double x)
        }
        if (ix < 0x3fdc0000) {    /* |x| < 0.4375 */
                if (ix < 0x3e400000) {  /* |x| < 2^-27 */
-                       /* raise inexact if x!=0 */
-                       FORCE_EVAL(x + 0x1p120f);
+                       if (ix < 0x00100000)
+                               /* raise underflow for subnormal x */
+                               FORCE_EVAL((float)x);
                        return x;
                }
                id = -1;