+#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE)
+#define M_E 2.7182818284590452354 /* e */
+#define M_LOG2E 1.4426950408889634074 /* log_2 e */
+#define M_LOG10E 0.43429448190325182765 /* log_10 e */
+#define M_LN2 0.69314718055994530942 /* log_e 2 */
+#define M_LN10 2.30258509299404568402 /* log_e 10 */
+#define M_PI 3.14159265358979323846 /* pi */
+#define M_PI_2 1.57079632679489661923 /* pi/2 */
+#define M_PI_4 0.78539816339744830962 /* pi/4 */
+#define M_1_PI 0.31830988618379067154 /* 1/pi */
+#define M_2_PI 0.63661977236758134308 /* 2/pi */
+#define M_2_SQRTPI 1.12837916709551257390 /* 2/sqrt(pi) */
+#define M_SQRT2 1.41421356237309504880 /* sqrt(2) */
+#define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */