bkrtoni's blog

By bkrtoni, history, 3 years ago, In English,
#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 */
 
 
 
 
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