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.TH MATH.H 3HEAD "Aug 11, 2004"
.SH NAME
math.h, math \- mathematical declarations
.SH SYNOPSIS
.LP
.nf
\fB#include <math.h>\fR
.fi

.SH DESCRIPTION
.sp
.LP
The <\fBmath.h\fR> header includes definitions for the following types:
.sp
.ne 2
.na
\fB\fBfloat_t\fR\fR
.ad
.RS 12n
A real-floating type at least as wide as \fBfloat\fR.
.RE

.sp
.ne 2
.na
\fB\fBdouble_t\fR\fR
.ad
.RS 12n
A real-floating type at least as wide as \fBdouble\fR, and at least as wide as
\fBfloat_t\fR.
.RE

.sp
.LP
If \fBFLT_EVAL_METHOD\fR equals 0, \fBfloat_t\fR and \fBdouble_t\fR are
\fBfloat\fR and \fBdouble\fR, respectively. If \fBFLT_EVAL_METHOD\fR equals 1,
they are both \fBdouble\fR. If \fBFLT_EVAL_METHOD\fR equals 2, they are both be
\fBlong double\fR. Other values of \fBFLT_EVAL_METHOD\fR are
implementation-defined.
.sp
.LP
The <\fBmath.h\fR> header provides the following constants. The values are of
type \fBdouble\fR and are accurate within the precision of the \fBdouble\fR
type.
.sp
.ne 2
.na
\fB\fBM_E\fR\fR
.ad
.RS 14n
The base of natural logarithms (\fIe\fR).
.RE

.sp
.ne 2
.na
\fB\fBM_LOG2E\fR\fR
.ad
.RS 14n
The base-2 logarithm of \fIe\fR.
.RE

.sp
.ne 2
.na
\fB\fBM_LOG10E\fR\fR
.ad
.RS 14n
The base-10 logarithm of \fIe\fR.
.RE

.sp
.ne 2
.na
\fB\fBM_LN2\fR\fR
.ad
.RS 14n
The natural logarithm of 2.
.RE

.sp
.ne 2
.na
\fB\fBM_LN10\fR\fR
.ad
.RS 14n
The natural logarithm of 10.
.RE

.sp
.ne 2
.na
\fB\fBM_PI\fR\fR
.ad
.RS 14n
\c
.if n pi\c
.if t \(*p
\c
, the ratio of the circumference of a circle to its diameter.
.RE

.sp
.ne 2
.na
\fB\fBM_PI_2\fR\fR
.ad
.RS 14n
\c
.if n pi\c
.if t \(*p
\c
/2.
.RE

.sp
.ne 2
.na
\fB\fBM_PI_4\fR\fR
.ad
.RS 14n
\c
.if n pi\c
.if t \(*p
\c
/4.
.RE

.sp
.ne 2
.na
\fB\fBM_1_PI\fR\fR
.ad
.RS 14n
1/\c
.if n pi\c
.if t \(*p
\c
.
.RE

.sp
.ne 2
.na
\fB\fBM_2_PI\fR\fR
.ad
.RS 14n
2/\c
.if n pi\c
.if t \(*p
\c
.
.RE

.sp
.ne 2
.na
\fB\fBM_2_SQRTPI\fR\fR
.ad
.RS 14n
2 over the square root of \c
.if n pi\c
.if t \(*p
\c
.
.RE

.sp
.ne 2
.na
\fB\fBM_SQRT2\fR\fR
.ad
.RS 14n
The positive square root of 2.
.RE

.sp
.ne 2
.na
\fB\fBM_SQRT1_2\fR\fR
.ad
.RS 14n
The positive square root of 1/2.
.RE

.sp
.LP
The <\fBmath.h\fR> header defines the following symbolic constants:
.sp
.ne 2
.na
\fB\fBMAXFLOAT\fR\fR
.ad
.RS 13n
The maximum value of a non-infinite single-precision floating point number.
.RE

.sp
.ne 2
.na
\fB\fBHUGE_VAL\fR\fR
.ad
.RS 13n
A positive \fBdouble\fR expression, not necessarily representable as a float.
Used as an error value returned by the mathematics library. \fBHUGE_VAL\fR
evaluates to +infinity on systems supporting IEEE Std 754-1985.
.RE

.sp
.ne 2
.na
\fB\fBHUGE_VALF\fR\fR
.ad
.RS 13n
A positive \fBfloat\fR constant expression. Used as an error value returned by
the mathematics library. \fBHUGE_VALF\fR evaluates to +infinity on systems
supporting IEEE Std 754-1985.
.RE

.sp
.ne 2
.na
\fB\fBHUGE_VALL\fR\fR
.ad
.RS 13n
A positive \fBlong double\fR constant expression. Used as an error value
returned by the mathematics library. \fBHUGE_VALL\fR evaluates to +infinity on
systems supporting IEEE Std 754-1985.
.RE

.sp
.ne 2
.na
\fB\fBINFINITY\fR\fR
.ad
.RS 13n
A constant expression of type \fBfloat\fR representing positive or unsigned
infinity, if available; else a positive constant of type \fBfloat\fR that
overflows at translation time.
.RE

.sp
.ne 2
.na
\fB\fBNAN\fR\fR
.ad
.RS 13n
A constant expression of type float representing a quiet NaN. This symbolic
constant is only defined if the implementation supports quiet NaNs for the
\fBfloat\fR type.
.RE

.sp
.LP
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
.sp
.in +2
.nf
FP_INFINITE
FP_NAN
FP_NORMAL
FP_SUBNORMAL
FP_ZERO
.fi
.in -2

.sp
.LP
The following optional macros indicate whether the \fBfma()\fR family of
functions are fast compared with direct code:
.sp
.in +2
.nf
FP_FAST_FMA
FP_FAST_FMAF
FP_FAST_FMAL
.fi
.in -2

.sp
.LP
The \fBFP_FAST_FMA\fR macro is defined to indicate that the \fBfma()\fR
function generally executes about as fast as, or faster than, a multiply and an
add of \fBdouble\fR operands. The other macros have the equivalent meaning for
the \fBfloat\fR and \fBlong double\fR versions.
.sp
.LP
The following macros expand to integer constant expressions whose values are
returned by \fBilogb\fR(\fIx\fR) if \fIx\fR is zero or NaN, respectively. The
value of \fBFP_ILOGB0\fR is either {\fBINT_MIN\fR} or -{\fBINT_MAX\fR}. The
value of \fBFP_ILOGBNAN\fR is either {\fBINT_MAX\fR} or {\fBINT_MIN\fR}.
.sp
.in +2
.nf
FP_ILOGB0
FP_ILOGBNAN
.fi
.in -2

.sp
.LP
The following macros expand to the integer constants 1 and 2, respectively:
.sp
.in +2
.nf
MATH_ERRNO
MATH_ERREXCEPT
.fi
.in -2

.sp
.LP
The following macro expands to an expression that has type \fBint\fR and the
value \fBMATH_ERREXCEPT\fR:
.sp
.in +2
.nf
math_errhandling
.fi
.in -2

.sp
.LP
The value of the macro \fBmath_errhandling\fR is constant for the duration of
the program. If a macro definition is suppressed or a program defines an
identifier with the name \fBmath_errhandling\fR, the behavior is undefined.
.sp
.LP
The <\fBmath.h\fR> header defines he following external variable:
.sp
.in +2
.nf
extern int signgam;
.fi
.in -2

.sp
.LP
The <\fBmath.h\fR> header defines the structure and constants used by the
\fBmatherr\fR(3M) error-handling mechanisms.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
.TE

.SH SEE ALSO
.sp
.LP
\fBIntro\fR(3), \fBfenv.h\fR(3HEAD), \fBlibm\fR(3LIB), \fBlimits.h\fR(3HEAD),
\fBmatherr\fR(3M), \fBattributes\fR(5), \fBstandards\fR(5)