Even more fixes for alpha Tru64, this time for

the phase and polar methods.

diff --git a/Modules/cmathmodule.c b/Modules/cmathmodule.c
index 347f88d9f8a9978d1f41a5702db2c768d63828cb..d6d1f27cb0944e43c4a2434d9fee07647cb3588b 100644 (file)
--- a/Modules/cmathmodule.c
+++ b/Modules/cmathmodule.c
@@ -264,7 +264,8 @@ c_atan(Py_complex z)
        return r;
 }
 
-/* Windows screws up atan2 for inf and nan */
+/* Windows screws up atan2 for inf and nan, and alpha Tru64 5.1 doesn't follow
+   C99 for atan2(0., 0.). */
 static double
 c_atan2(Py_complex z)
 {
@@ -282,6 +283,14 @@ c_atan2(Py_complex z)
                /* atan2(+-inf, x) == +-pi/2 for finite x */
                return copysign(0.5*Py_MATH_PI, z.imag);
        }
+       if (Py_IS_INFINITY(z.real) || z.imag == 0.) {
+               if (copysign(1., z.real) == 1.)
+                       /* atan2(+-y, +inf) = atan2(+-0, +x) = +-0. */
+                       return copysign(0., z.imag);
+               else
+                       /* atan2(+-y, -inf) = atan2(+-0., -x) = +-pi. */
+                       return copysign(Py_MATH_PI, z.imag);
+       }
        return atan2(z.imag, z.real);
 }