cos(), cosf(), cosl()

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: (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 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:

C11, POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	Yes
Signal handler	Yes
Thread	Yes