cos(), cosf(), cosl()
QNX SDP8.0C Library ReferenceAPIDeveloper
Compute the cosine of an angle
Synopsis:
#include <math.h>
double cos( double x );
float cosf( float x );
long double cosl( long double x );
Arguments:
- x
 - The angle, in radians, for which you want to compute the cosine.
 
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 cosine of x radians.
Note: 
An argument with a large magnitude may yield results with little or no significance.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
- Call 
feclearexcept(FE_ALL_EXCEPT)before calling cos(), cosf(), or cosl(). - On return, if 
fetestexcept(FE_ALL_EXCEPT)is nonzero, then an error has occurred. 
Returns:
The cosine of x.
| If x is: | These functions return: | Errors: | 
|---|---|---|
| ±0.0 | 1.0 | — | 
| ±Inf | NaN | FE_INVALID | 
| NaN | NaN | — | 
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 )
{
    double value;
    int except_flags;
    feclearexcept(FE_ALL_EXCEPT);
    value = cos( M_PI );
    printf( "The cosine of pi is %f\n", value );
    except_flags = fetestexcept(FE_ALL_EXCEPT);
    if(except_flags) {
        /* An error occurred; handle it appropriately. */
    }
    return EXIT_SUCCESS;
}
produces the output:
value = -1.000000
Classification:
| Safety: | |
|---|---|
| Cancellation point | No | 
| Signal handler | Yes | 
| Thread | Yes | 
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