math(5)                                                             math(5)




 NAME    [Toc]    [Back]
      math - math functions, constants, and types

 SYNOPSIS    [Toc]    [Back]
      #include <math.h>

 DESCRIPTION    [Toc]    [Back]
      This file contains declarations of all the functions in the Math
      Library (described in Section (3M)).

      For Itanium(R)-based systems, included in a compilation under the
      -fpwidetypes option, this file defines the types

           extended    The Itanium-based 80-bit double-extended type.

           quad        An IEEE 754-compliant, 128-bit floating-point type.
                       On HPUX, quad is a synonym for long double.

      It defines the types

           float_t     A floating type, at least as wide as float.  For PARISC,
 float_t is float.  For Itanium-based system, if
                       FLT_EVAL_METHOD equals 0, float_t is float; if
                       FLT_EVAL_METHOD equals 1, float_t is double; if
                       FLT_EVAL_METHOD equals -2, float_t is extended.

           double_t    A floating type, at least as wide as double.  For
                       PA-RISC, double_t is double.  For Itanium-based
                       system, if FLT_EVAL_METHOD equals 0 or 1, double_t is
                       double; if FLT_EVAL_METHOD equals -2, double_t is
                       extended.

      For Itanium-based system, the value of FLT_EVAL_METHOD is 0, 1, or -2,
      according to the use of the compiler option -fpeval=float(default), -
      fpeval=double, or -fpeval=extended.

      It defines the following constants, which, for Itanium-based system,
      may be used to initialize statics and aggregates:

           NAN         A quiet NaN (Not-a-Number) value (type float).

           INFINITY    A positive infinity value (type float).

           HUGE_VAL    The maximum value (type double) representable in the
                       double type (IEEE positive infinity).

           HUGE_VALF   The maximum value (type float) representable in the
                       float type (IEEE positive infinity).

           HUGE_VALL   For Itanium-based system only, the maximum value
                       (type long double) representable in the long double



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 math(5)                                                             math(5)




                       type (IEEE positive infinity).

           HUGE_VALW   For Itanium-based system only, the maximum value
                       (type extended) representable in the extended type
                       (IEEE positive infinity).  To use HUGE_VALW compile
                       with the -fpwidetypes option.

           HUGE_VALQ   For Itanium-based system only, equivalent to
                       HUGE_VALL.  To use HUGE_VALQ compile with the
                       -fpwidetypes option.

      It defines the following integer constants which give special-case
      values returned by the ilogb() functions:

           FP_ILOGB0   Returned by ilogb() if its argument is zero.

           FP_ILOGBNAN Returned by ilogb() if its argument is a NaN.

      For Itanium-based system, it defines the following integer constants
      which identify the error handling method supported by <math.h>
      functions:

           MATH_ERRNO  Indicates support for the ISO/IEC C99 errno
                       specification.

           MATH_ERREXCEPT    [Toc]    [Back]
                       Indicates support for the ISO/IEC C99 exception flag
                       specification.

           math_errhandling
                       Defined to be MATH_ERRNO if the +Olibmerrno compiler
                       option (not the default) is used, or defined to be
                       MATH_ERREXCEPT otherwise.

      It defines the following mathematical constants (type double) for user
      convenience:

           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.  (There are also several fractions of pi,
                       its reciprocal, and its square root: M_PI_2, M_PI_4,
                       M_1_PI, M_2_PI, and M_2_SQRTPI).



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 math(5)                                                             math(5)




           M_SQRT2     The positive square root of 2.

           M_SQRT1_2   The positive square root of 1/2.

      For the definitions of various machine-dependent constants, see the
      description of the <values.h> header file.

      To use one of the types extended or quad, or one of the macros
      HUGE_VALW or HUGE_VALQ, compile with the -fpwidetypes option.

 FILES    [Toc]    [Back]
      /usr/include/math.h

 SEE ALSO    [Toc]    [Back]
      intro(3), complex(5), fenv(5), values(5).

 STANDARDS CONFORMANCE    [Toc]    [Back]
      <math.h>: SVID3, XPG4.2, ANSI C, ISO/IEC C99


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