sincosl

sincosl is a function provided by some C math libraries that computes both the sine and the cosine of a long double value in a single call. It is designed to improve performance and accuracy by allowing the implementation to share common work, such as argument reduction, between the two trigonometric computations.

Signature and behavior: the typical form is void sincosl(long double x, long double *sinp, long double *cosp); The function writes the sine of x to the location pointed to by sinp and the cosine of x to the location pointed to by cosp, and returns no value. For example, sincosl(0.5L, &s, &c) stores sin(0.5) in s and cos(0.5) in c.

Rationale and usage: computing both sin and cos in one call can reduce computational effort and improve numerical consistency, since both results are derived from the same reduced argument. This can be beneficial in iterative or simultaneous evaluation contexts.

Availability and portability: sincosl is not part of the ISO C standard; it is provided as an extension by some C libraries, such as the GNU C Library (glibc) and others on Unix-like systems. Its presence varies by platform and compiler. When portability is required, programmers may fall back to separate calls to sinl and cosl.

Related functions: there are equivalent variants for other floating-point precisions, including sincos (double) and sincosf (float). The long double version is sincosl.

See also: sin, cos, sincos (double), sincosf (float), sincosl (long double).