"Senturon" <senturontemp-at-charter-dot-net> wrote in message
news:10*************@corp.supernews.com...
I was wondering what, if there is even one, the syntax for the constant e
is. I figured it would be in math.h right alongside 'pi' but it doesn't
seem to be there, does it in fact exist? i did many searches online but it
is hard to search for the letter 'e', even tried natural logs but came up
dry. Any help would be appreciated, thank you!
~Senturon
AFAIK, there is no C standard for common math constants but most Unix
implementations have them in <math.h>, all with a prefix of "M_". Microsoft
did not include these constants until VC7 and then only if you define the
symbol _USE_MATH_DEFINES as demonstrated below.
The constant for e is: M_E
Dag
From VC7 math.h:
#ifdef _USE_MATH_DEFINES
/* 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 */