sincos(), sincosf(), sincosl()

QNX SDP8.0C Library ReferenceAPIDeveloper

Calculate the sine and cosine of an angle

Synopsis:

#include <math.h>

void sincos( double x, double *sn, double *cs );

void sincosf( float x, float *sn, float *cs);

void sincosl( long double x, long double *sn, long double *cs );

Arguments:

x
The angle, in radians, for which you want to compute the sine and cosine.
sn
The sine of angle x.
cs
The cosine of angle x.

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:

The sincos(), sincosf(), and sincosl() functions compute the sine and cosine of x in radians. These functions let argument reduction occur once instead of twice with independent calls to sin() and cos(). An argument with a large magnitude 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 sincos(), sincosf(), or sincosl().
  • On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

Returns:

If x is: These functions return: Errors:
±0.0 0.0 (sn) and 1.0 (cs) —
±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 )
{
int except_flags;
double sin_result, cos_result;

feclearexcept(FE_ALL_EXCEPT);

sincos( 0.5, &sin_result, &cos_result);
printf( "%f %f\n", sin_result, cos_result);

except_flags = fetestexcept(FE_ALL_EXCEPT);
if(except_flags) {
/* An error occurred; handle it appropriately. */
}

return EXIT_SUCCESS;
}
The code produces the following output: 
0.479426 0.877583

Classification:

C11, POSIX 1003.1

Safety:
Cancellation point No
Signal handler Yes
Thread Yes
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