SINCOS(3) Linux Programmer's Manual SINCOS(3)

sincos, sincosf, sincosl - calculate sin and cos simultaneously

#define _GNU_SOURCE         /* See feature_test_macros(7) */
#include <math.h>
void sincos(double x, double *sin, double *cos);
void sincosf(float x, float *sin, float *cos);
void sincosl(long double x, long double *sin, long double *cos);
Link with -lm.

Several applications need sine and cosine of the same angle x. These functions compute both at the same time, and store the results in *sin and *cos. Using this function can be more efficient than two separate calls to sin(3) and cos(3).
If x is a NaN, a NaN is returned in *sin and *cos.
If x is positive infinity or negative infinity, a domain error occurs, and a NaN is returned in *sin and *cos.

These functions return void.

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
Domain error: x is an infinity
An invalid floating-point exception (FE_INVALID) is raised.
These functions do not set errno.

These functions first appeared in glibc in version 2.1.

For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
sincos (), sincosf (), sincosl () Thread safety MT-Safe

These functions are GNU extensions.

To see the performance advantage of sincos(), it may be necessary to disable gcc(1) built-in optimizations, using flags such as:

cc -O -lm -fno-builtin prog.c

cos(3), sin(3), tan(3)
2017-09-15 GNU