__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
Mac OS X 10.9.1 - Generated Fri Jan 10 06:04:45 CST 2014