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man pages section 3: Library Interfaces and Headers

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Updated: Thursday, June 13, 2019
 
 

math(3HEAD)

Name

math.h, math - mathematical declarations

Synopsis

#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

π, the ratio of the circumference of a circle to its diameter.

M_PI_2

π/2.

M_PI_4

π/4.

M_1_PI

1/π.

M_2_PI

2/π.

M_2_SQRTPI

2 over the square root of π.

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 the 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(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
Standard

See Also

fenv.h(3HEAD), limits.h(3HEAD), libm(3LIB), matherr(3M), intro(3), attributes(7), standards(7)