Calculate the tangent of an angle
Synopsis:
#include <math.h>
double tan( double x );
float tanf( float x );
long double tanl( long double x );
Arguments:
 x
 The angle, in radians, for which you want to compute the tangent.
Library:
 libm
 The generalpurpose math library.
 libmsve
 (QNX Neutrino 7.1 or later)
A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.
Your system requirements will determine how you should work with these libraries:
 If you want only selected processes to run with the SVE version, you can include both libraries in your OS image
and use the l m or l msve option to
qcc
to link explicitly against the appropriate one.
 If you want all processes to use the SVE version, include libmsve.so in your OS image
and set up a symbolic link from libm.so to libmsve.so.
Use the l m option to
qcc
to link against the library.
Note:
Compile your program with the fnobuiltin option to prevent the compiler from using a
builtin version of the function.
Description:
These functions compute the tangent of x radians.
A large magnitude argument may yield a result with little or no significance.
To check for error situations, use
feclearexcept()
and
fetestexcept().
For example:
 Call feclearexcept(FE_ALL_EXCEPT) before calling
tan(), tanf(), or tanl().
 On return, if fetestexcept(FE_ALL_EXCEPT)
is nonzero, then an error has occurred.
Returns:
The tangent value.
If x is: 
These functions return: 
Errors: 
±0.0 
x 
— 
±Inf 
NaN 
FE_INVALID 
NaN 
NaN 
— 
Subnormal 
x 
— 
Note:
The tangent function has mathematical poles at
..., π/2, π/2, 3 * π/2, ...,
but these numbers can't be expressed exactly in floatingpoint representation, so no
FE_DIVBYZERO errors occur.
These functions raise FE_INEXACT if the FPU reports that
the result can't be exactly represented as a floatingpoint number.
Examples:
#include <stdio.h>
#include <math.h>
#include <fenv.h>
#include <stdlib.h>
int main( void )
{
int except_flags;
feclearexcept(FE_ALL_EXCEPT);
printf( "%f\n", tan(.5) );
except_flags = fetestexcept(FE_ALL_EXCEPT);
if(except_flags) {
/* An error occurred; handle it appropriately. */
}
return EXIT_SUCCESS;
}
produces the output:
0.546302
Classification:
C11,
POSIX 1003.1
Safety: 

Cancellation point 
No 
Interrupt handler 
Yes 
Signal handler 
Yes 
Thread 
Yes 