# man pages section 3: Extended Library Functions, Volume 4

Updated: Thursday, June 13, 2019

## atan2df (3SUNMATH)

### Name

sind, sindf, sindl, cosd, cosdf, cosdl, tand, tandf, tandl, sincosd, sincosdf, sincosdl, asind, asindf, asindl, acosd, acosdf, acosdl, atand, atandf, atandl, atan2d, atan2df, atan2dl - degree-based trigonometric functions

### Synopsis

cc [ flag ... ] file ...  -lsunmath -lm [ library ... ]
#include <sunmath.h>
double sind(double x);
float sindf(float x);
long double sindl(long double x);
double cosd(double x);
float cosdf(float x);
long double cosdl(long double x);
double tand(double x);
float tandf(float x);
long double tandl(long double x);
void sincosd(double x, double *s, double *c);
void sincosdf(float x, float *s, float *c);
void  sincosdl(long  double  x,  long double *s, long double *c);
double asind(double x);
float asindf(float x);
long double asindl(long double x);
double acosd(double x);
float acosdf(float x);
long double acosdl(long double x);
double atand(double x);
float atandf(float x);
long double atandl(long double x);
double atan2d(double y, double x);
float atan2df(float y, float x);
long double atan2dl(long double y, long double x);

### Description

sind(x), cosd(x), and tand(x) compute trigonometric functions of angles measured in degrees: sind(x) := sin(x * pi/180), and similarly for cosd(x) and tand(x).

sincosd(x, s, c) simultaneously sets *s = sind(x) and *c = cosd(x).

The corresponding inverse functions compute asind(x) := asin(x) * 180/pi, and similarly for acosd(x) and atand(x). Also, atan2d(y, x) := atan2(y, x) * 180/pi.

### Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
MT-Level
MT-Safe
Availability
system/library/math