__SINPI(3) BSD Library Functions Manual __SINPI(3)NAME__sinpi — sine-pi function
SYNOPSIS
#include <math.h>
float
__sinpif(float x);
double
__sinpi(double x);
DESCRIPTION
The __sinpi() function returns the sine of pi times x (measured in radi‐
ans). This can be computed more accurately than sin(M_PI * x), because
it can implicitly use as many bits of pi as are necessary to deliver a
well-rounded result, instead of the 53-bits to which M_PI is limited.
For large x it may also be more efficient, as the argument reduction
involved is significantly simpler.
This function may be especially useful for working with degrees; whereas
sin(M_PI * x / 180.0) cannot produce exact results for angles that
naively "should" be exact, like 180 degrees, __sinpi(x / 180.0) can be
computed exactly.
SPECIAL VALUES
__sinpi(-x) is the same as - __sinpi(x) for any finite x.
__sinpi(�0) returns �0.
__sinpi(n) returns +0 for any positive integer n.
__sinpi(n + 0.5) returns +1 for any even integer n.
__sinpi(n + 0.5) returns -1 for any odd integer n.
__sinpi(�infinity) raises the invalid floating-point exception and
returns NaN.
VECTOR OPERATIONS
If you need to apply the __sinpi() function to SIMD vectors or arrays,
using the following functions provided by the Accelerate.framework may be
useful:
#include <Accelerate/Accelerate.h>
vFloat vsinpif(vFloat x);
void vvsinpif(float *y, float *x, const int n);
void vvsinpi(double *y, double *x, const int n);
SEE ALSO__cospi(3), __tanpi(3), __sincospi(3), math(3)BSD December 15, 2012 BSD
