# m_ln2(3) [osx man page]

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

constantsmathematical 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

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math.h(3HEAD) Headers math.h(3HEAD)NAME

math.h, math - mathematical declarationsSYNOPSIS

#include <math.h>DESCRIPTION

The <math.h> header includes definitions for the following types: float_t A real-floating type at least as wide as float. double_t A real-floating type at least as wide as double, and at least as wide as float_t. If FLT_EVAL_METHOD equals 0, float_t and double_t are float and double, respectively. If FLT_EVAL_METHOD equals 1, they are both double. If FLT_EVAL_METHOD equals 2, they are both be long double. Other values of FLT_EVAL_METHOD are implementation-defined. The <math.h> header provides the following constants. The values are of type double and are accurate within the precision of the double type. M_E The base of natural logarithms (e). M_LOG2E The base-2 logarithm of e. M_LOG10E The base-10 logarithm of e. M_LN2 The natural logarithm of 2. M_LN10 The natural logarithm of 10. M_PI , the ratio of the circumference of a circle to its diameter. M_PI_2 /2. M_PI_4 /4. M_1_PI 1/. M_2_PI 2/. M_2_SQRTPI 2 over the square root of . M_SQRT2 The positive square root of 2. M_SQRT1_2 The positive square root of 1/2. The <math.h> header defines the following symbolic constants: MAXFLOAT The maximum value of a non-infinite single-precision floating point number. HUGE_VAL A positive double expression, not necessarily representable as a float. Used as an error value returned by the mathematics library. HUGE_VAL evaluates to +infinity on systems supporting IEEE Std 754-1985. HUGE_VALF A positive float constant expression. Used as an error value returned by the mathematics library. HUGE_VALF evaluates to +infinity on systems supporting IEEE Std 754-1985. HUGE_VALL A positive long double constant expression. Used as an error value returned by the mathematics library. HUGE_VALL evaluates to +infinity on systems supporting IEEE Std 754-1985. INFINITY A constant expression of type float representing positive or unsigned infinity, if available; else a positive constant of type float that overflows at translation time. NAN A constant expression of type float representing a quiet NaN. This symbolic constant is only defined if the implementation supports quiet NaNs for the float type. The following macros are defined for number classification. They represent the mutually-exclusive kinds of floating-point values. They expand to integer constant expressions with distinct values FP_INFINITE FP_NAN FP_NORMAL FP_SUBNORMAL FP_ZERO The following optional macros indicate whether the fma() family of functions are fast compared with direct code: FP_FAST_FMA FP_FAST_FMAF FP_FAST_FMAL The FP_FAST_FMA macro is defined to indicate that the fma() function generally executes about as fast as, or faster than, a multiply and an add of double operands. The other macros have the equivalent meaning for the float and long double versions. The following macros expand to integer constant expressions whose values are returned by ilogb(x) if x is zero or NaN, respectively. The value of FP_ILOGB0 is either {INT_MIN} or -{INT_MAX}. The value of FP_ILOGBNAN is either {INT_MAX} or {INT_MIN}. FP_ILOGB0 FP_ILOGBNAN The following macros expand to the integer constants 1 and 2, respectively: MATH_ERRNO MATH_ERREXCEPT The following macro expands to an expression that has type int and the value MATH_ERREXCEPT: math_errhandling The value of the macro math_errhandling is constant for the duration of the program. If a macro definition is suppressed or a program defines an identifier with the name math_errhandling, the behavior is undefined. The <math.h> header defines he following external variable: extern int signgam; The <math.h> header defines the structure and constants used by the matherr(3M) error-handling mechanisms.ATTRIBUTES

See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+SEE ALSO

intro(3), fenv.h(3HEAD), libm(3LIB), limits.h(3HEAD), matherr(3M), attributes(5), standards(5)SunOS 5.1011 Aug 2004 math.h(3HEAD)