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.TH tan 3M "12 Jul 2006" "SunOS 5.11" "Mathematical Library Functions"
.SH NAME
tan, tanf, tanl \- tangent function
.SH SYNOPSIS
.LP
.nf
c99 [ \fIflag\fR... ] \fIfile\fR... \fB-lm\fR [ \fIlibrary\fR... ]
#include <math.h>

\fBdouble\fR \fBtan\fR(\fBdouble\fR \fIx\fR);
.fi

.LP
.nf
\fBfloat\fR \fBtanf\fR(\fBfloat\fR \fIx\fR);
.fi

.LP
.nf
\fBlong double\fR \fBtanl\fR(\fBlong double\fR \fIx\fR);
.fi

.SH DESCRIPTION
.sp
.LP
These functions compute the tangent of their argument \fIx\fR, measured in
radians.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, these functions return the tangent of \fIx\fR.
.sp
.LP
If \fIx\fR is NaN, a NaN is returned.
.sp
.LP
If \fIx\fR is \(+-0, \fIx\fR is returned.
.sp
.LP
If \fIx\fR is \(+-Inf, a domain error occurs and a NaN is returned.
.SH ERRORS
.sp
.LP
These functions will fail if:
.sp
.ne 2
.mk
.na
\fBDomain Error\fR
.ad
.RS 16n
.rt  
The value of \fIx\fR is \(+-Inf.
.sp
If the integer expression (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR) is
non-zero, the invalid floating-point exception is raised.
.RE

.SH USAGE
.sp
.LP
There are no known floating-point representations such that for a normal
argument, \fBtan\fR(\fIx\fR) is either overflow or underflow.
.sp
.LP
An application wanting to check for exceptions should call
\fBfeclearexcept\fR(\fBFE_ALL_EXCEPT\fR) before calling these functions. On
return, if \fBfetestexcept\fR(\fBFE_INVALID\fR | \fBFE_DIVBYZERO\fR |
\fBFE_OVERFLOW\fR | \fBFE_UNDERFLOW\fR) is non-zero, an exception has been
raised. An application should either examine the return value or check the
floating point exception flags to detect exceptions.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityStandard
_
MT-LevelMT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBatan\fR(3M), \fBfeclearexcept\fR(3M), \fBfetestexcept\fR(3M),
\fBisnan\fR(3M), \fBmath.h\fR(3HEAD), \fBattributes\fR(5), \fBstandards\fR(5)