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POSIX 1003.1 - man page for math.h (posix section 0p)

<math.h>(P)			    POSIX Programmer's Manual			      <math.h>(P)

NAME
       math.h - mathematical declarations

SYNOPSIS
       #include <math.h>

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 values of FLT_EVAL_METHOD, they are otherwise  imple-
       mentation-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 mathe-
	      matics  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 con-
	      stant 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  mutu-
       ally-exclusive kinds of floating-point values. They expand to integer constant expressions
       with distinct values. Additional  implementation-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 com-
       pared 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 exe-
       cutes 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 unspeci-
       fied whether math_errhandling 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 provided.

	      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  argu-
       ments,  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 implementation to contract expressions. Each pragma can occur either outside
       external declarations or preceding all explicit declarations and statements inside a  com-
       pound  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_CONTRACT pragma is encountered (including within a nested compound state-
       ment),  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 sys-
       tems supporting the Legacy Option Group.

FUTURE DIRECTIONS
       None.

SEE ALSO
       <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(), remainder(), 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, Standard for Information Technology  --  Portable	Operating  System
       Interface  (POSIX), The Open Group Base Specifications 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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				      <math.h>(P)


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