tan(), tanf(), tanl()
QNX SDP8.0C Library ReferenceAPIDeveloper
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 general-purpose math library.
- libm-sve
- 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 m-sve option to qcc to link explicitly against the appropriate one.
- If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.
Note:
Compile your program with the -fno-builtin option to prevent the compiler from using a
built-in 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 floating-point 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 floating-point 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:
Safety: | |
---|---|
Cancellation point | No |
Signal handler | Yes |
Thread | Yes |
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