0p:math.h
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math.h - mathematical declarations
#include <math.h>
Contents |
DESCRIPTION
Some of the functionality described on this reference page extends the ISO C standard. Applications shall define
the appropriate feature test macro (see the System Interfaces volume of IEEE Std 1003.1-2001, Section 2.2, The
Compilation Environment) to enable the visibility of these symbols in this header.
The <math.h> header shall include definitions for at least 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 shall be float and double, respectively; if FLT_EVAL_METHOD
equals 1, they shall both be double; if FLT_EVAL_METHOD equals 2, they shall both be long double; for other val-
ues of FLT_EVAL_METHOD, they are otherwise implementation-defined.
The <math.h> header shall define the following macros, where real-floating indicates that the argument shall be
an expression of real-floating type:
int fpclassify(real-floating x);
int isfinite(real-floating x);
int isinf(real-floating x);
int isnan(real-floating x);
int isnormal(real-floating x);
int signbit(real-floating x);
int isgreater(real-floating x, real-floating y);
int isgreaterequal(real-floating x, real-floating y);
int isless(real-floating x, real-floating y);
int islessequal(real-floating x, real-floating y);
int islessgreater(real-floating x, real-floating y);
int isunordered(real-floating x, real-floating y);
The <math.h> header shall provide for the following constants. The values are of type double and are accurate
within the precision of the double type.
M_E Value of e
M_LOG2E
Value of log_2e
M_LOG10E
Value of log_10e
M_LN2 Value of log_e2
M_LN10 Value of log_e10
M_PI Value of pi
M_PI_2 Value of pi/2
M_PI_4 Value of pi/4
M_1_PI Value of 1/pi
M_2_PI Value of 2/pi
M_2_SQRTPI
Value of 2/ sqrt pi
M_SQRT2
Value of sqrt 2
M_SQRT1_2
Value of 1/sqrt 2
The header shall define the following symbolic constants:
MAXFLOAT
Value of maximum 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 posi-
tive 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 shall be defined for number classification. They represent the mutually-exclusive kinds of
floating-point values. They expand to integer constant expressions with distinct values. Additional implementa-
tion-defined floating-point classifications, with macro definitions beginning with FP_ and an uppercase letter,
may also be specified by the implementation.
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 shall be 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 shall expand to integer constant expressions whose values are returned by ilogb( x) if x is
zero or NaN, respectively. The value of FP_ILOGB0 shall be either {INT_MIN} or - {INT_MAX}. The value of
FP_ILOGBNAN shall be either {INT_MAX} or {INT_MIN}.
FP_ILOGB0
FP_ILOGBNAN
The following macros shall expand to the integer constants 1 and 2, respectively;
MATH_ERRNO
MATH_ERREXCEPT
The following macro shall expand to an expression that has type int and the value MATH_ERRNO, MATH_ERREXCEPT, or
the bitwise-inclusive OR of both:
math_errhandling
The value of math_errhandling is constant for the duration of the program. It is unspecified whether math_errhan-
dling is a macro or an identifier with external linkage. If a macro definition is suppressed or a program defines
an identifier with the name math_errhandling , the behavior is undefined. If the expression (math_errhandling &
MATH_ERREXCEPT) can be non-zero, the implementation shall define the macros FE_DIVBYZERO, FE_INVALID, and
FE_OVERFLOW in <fenv.h>.
The following shall be declared as functions and may also be defined as macros. Function prototypes shall be pro-
vided.
double acos(double);
float acosf(float);
double acosh(double);
float acoshf(float);
long double acoshl(long double);
long double acosl(long double);
double asin(double);
float asinf(float);
double asinh(double);
float asinhf(float);
long double asinhl(long double);
long double asinl(long double);
double atan(double);
double atan2(double, double);
float atan2f(float, float);
long double atan2l(long double, long double);
float atanf(float);
double atanh(double);
float atanhf(float);
long double atanhl(long double);
long double atanl(long double);
double cbrt(double);
float cbrtf(float);
long double cbrtl(long double);
double ceil(double);
float ceilf(float);
long double ceill(long double);
double copysign(double, double);
float copysignf(float, float);
long double copysignl(long double, long double);
double cos(double);
float cosf(float);
double cosh(double);
float coshf(float);
long double coshl(long double);
long double cosl(long double);
double erf(double);
double erfc(double);
float erfcf(float);
long double erfcl(long double);
float erff(float);
long double erfl(long double);
double exp(double);
double exp2(double);
float exp2f(float);
long double exp2l(long double);
float expf(float);
long double expl(long double);
double expm1(double);
float expm1f(float);
long double expm1l(long double);
double fabs(double);
float fabsf(float);
long double fabsl(long double);
double fdim(double, double);
float fdimf(float, float);
long double fdiml(long double, long double);
double floor(double);
float floorf(float);
long double floorl(long double);
double fma(double, double, double);
float fmaf(float, float, float);
long double fmal(long double, long double, long double);
double fmax(double, double);
float fmaxf(float, float);
long double fmaxl(long double, long double);
double fmin(double, double);
float fminf(float, float);
long double fminl(long double, long double);
double fmod(double, double);
float fmodf(float, float);
long double fmodl(long double, long double);
double frexp(double, int *);
float frexpf(float value, int *);
long double frexpl(long double value, int *);
double hypot(double, double);
float hypotf(float, float);
long double hypotl(long double, long double);
int ilogb(double);
int ilogbf(float);
int ilogbl(long double);
double j0(double);
double j1(double);
double jn(int, double);
double ldexp(double, int);
float ldexpf(float, int);
long double ldexpl(long double, int);
double lgamma(double);
float lgammaf(float);
long double lgammal(long double);
long long llrint(double);
long long llrintf(float);
long long llrintl(long double);
long long llround(double);
long long llroundf(float);
long long llroundl(long double);
double log(double);
double log10(double);
float log10f(float);
long double log10l(long double);
double log1p(double);
float log1pf(float);
long double log1pl(long double);
double log2(double);
float log2f(float);
long double log2l(long double);
double logb(double);
float logbf(float);
long double logbl(long double);
float logf(float);
long double logl(long double);
long lrint(double);
long lrintf(float);
long lrintl(long double);
long lround(double);
long lroundf(float);
long lroundl(long double);
double modf(double, double *);
float modff(float, float *);
long double modfl(long double, long double *);
double nan(const char *);
float nanf(const char *);
long double nanl(const char *);
double nearbyint(double);
float nearbyintf(float);
long double nearbyintl(long double);
double nextafter(double, double);
float nextafterf(float, float);
long double nextafterl(long double, long double);
double nexttoward(double, long double);
float nexttowardf(float, long double);
long double nexttowardl(long double, long double);
double pow(double, double);
float powf(float, float);
long double powl(long double, long double);
double remainder(double, double);
float remainderf(float, float);
long double remainderl(long double, long double);
double remquo(double, double, int *);
float remquof(float, float, int *);
long double remquol(long double, long double, int *);
double rint(double);
float rintf(float);
long double rintl(long double);
double round(double);
float roundf(float);
long double roundl(long double);
double scalb(double, double);
double scalbln(double, long);
float scalblnf(float, long);
long double scalblnl(long double, long);
double scalbn(double, int);
float scalbnf(float, int);
long double scalbnl(long double, int);
double sin(double);
float sinf(float);
double sinh(double);
float sinhf(float);
long double sinhl(long double);
long double sinl(long double);
double sqrt(double);
float sqrtf(float);
long double sqrtl(long double);
double tan(double);
float tanf(float);
double tanh(double);
float tanhf(float);
long double tanhl(long double);
long double tanl(long double);
double tgamma(double);
float tgammaf(float);
long double tgammal(long double);
double trunc(double);
float truncf(float);
long double truncl(long double);
double y0(double);
double y1(double);
double yn(int, double);
The following external variable shall be defined:
extern int signgam;
The behavior of each of the functions defined in <math.h> is specified in the System Interfaces volume of
IEEE Std 1003.1-2001 for all representable values of its input arguments, except where stated otherwise. Each
function shall execute as if it were a single operation without generating any externally visible exceptional
conditions.
The following sections are informative.
APPLICATION USAGE
The FP_CONTRACT pragma can be used to allow (if the state is on) or disallow (if the state is off) the implemen-
tation to contract expressions. Each pragma can occur either outside external declarations or preceding all
explicit declarations and statements inside a compound statement. When outside external declarations, the pragma
takes effect from its occurrence until another FP_CONTRACT pragma is encountered, or until the end of the trans-
lation unit. When inside a compound statement, the pragma takes effect from its occurrence until another FP_CON-
TRACT pragma is encountered (including within a nested compound statement), or until the end of the compound
statement; at the end of a compound statement the state for the pragma is restored to its condition just before
the compound statement. If this pragma is used in any other context, the behavior is undefined. The default state
(on or off) for the pragma is implementation-defined.
RATIONALE
Before the ISO/IEC 9899:1999 standard, the math library was defined only for the floating type double. All the
names formed by appending 'f' or 'l' to a name in <math.h> were reserved to allow for the definition of float and
long double libraries; and the ISO/IEC 9899:1999 standard provides for all three versions of math functions.
The functions ecvt(), fcvt(), and gcvt() have been dropped from the ISO C standard since their capability is
available through sprintf(). These are provided on XSI-conformant systems supporting the Legacy Option Group.
FUTURE DIRECTIONS
None.
RELATED
<stddef.h> , <sys/types.h> , the System Interfaces volume of IEEE Std 1003.1-2001, acos(), acosh(), asin(),
atan(), atan2(), cbrt(), ceil(), cos(), cosh(), erf(), exp(), expm1(), fabs(), floor(), fmod(), frexp(), hypot(),
ilogb(), isnan(), j0(), ldexp(), lgamma(), log(), log10(), log1p(), logb(), modf(), nextafter(), pow(), remain-
der(), rint(), scalb(), sin(), sinh(), sqrt(), tan(), tanh(), y0()
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
tions Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open
Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 <math.h>(P)