#if defined(_USE_MATH_DEFINES) && !defined(_MATH_DEFINES_DEFINED) #define _MATH_DEFINES_DEFINED /* Define _USE_MATH_DEFINES before including math.h to expose these macro * definitions for common math constants. These are placed under an #ifdef * since these commonly-defined names are not part of the C/C++ standards. */ /* Definitions of useful mathematical constants * M_E - e * M_LOG2E - log2(e) * M_LOG10E - log10(e) * M_LN2 - ln(2) * M_LN10 - ln(10) * M_PI - pi * M_PI_2 - pi/2 * M_PI_4 - pi/4 * M_1_PI - 1/pi * M_2_PI - 2/pi * M_2_SQRTPI - 2/sqrt(pi) * M_SQRT2 - sqrt(2) * M_SQRT1_2 - 1/sqrt(2) */ #define M_E 2.71828182845904523536 #define M_LOG2E 1.44269504088896340736 #define M_LOG10E 0.434294481903251827651 #define M_LN2 0.693147180559945309417 #define M_LN10 2.30258509299404568402 #define M_PI 3.14159265358979323846 #define M_PI_2 1.57079632679489661923 #define M_PI_4 0.785398163397448309616 #define M_1_PI 0.318309886183790671538 #define M_2_PI 0.636619772367581343076 #define M_2_SQRTPI 1.12837916709551257390 #define M_SQRT2 1.41421356237309504880 #define M_SQRT1_2 0.707106781186547524401 #endif /* _USE_MATH_DEFINES */
math.h Wrote:These are placed under an #ifdef since these commonly-defined names are not part of the C/C++ standards.