osx man page for m_e

M_PI(3) 						   BSD Library Functions Manual 						   M_PI(3)

NAME
     constants -- mathematical library constants

SYNOPSIS
     #include <math.h>

DESCRIPTION
     The header file math.h provides macros that define a number of useful numerical constants.

LIST OF CONSTANTS
     As required by the POSIX standard, these constants are double-precision literals, with enough digits specified as to ensure that they are
     correctly rounded in double-precision:

     M_E

     "Euler's constant" or e; the base of the natural logarithm.

     M_LOG2E
     M_LOG10E

     The logarithms of e in base 2 and 10, respectively.

     M_LN2
     M_LN10

     The natural logarithms of 2 and 10, respectively.	Note that these are the reciprocals of the preceeding two values.

     M_PI
     M_PI_2
     M_PI_4

     pi, pi/2, and pi/4, respectively.

     M_1_PI
     M_2_PI

     1/pi and 2/pi, respectively.

     M_2_SQRTPI

     Two divided by the square root of pi.

     M_SQRT2
     M_SQRT_1_2

     The square root of two and its reciprocal, respectively.

SEE ALSO
     math(3), float(3),

STANDARDS
     The <math.h> functions and macros conform to the ISO/IEC 9899:2011 standard.

BSD
								   July 6, 2010 							       BSD