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Manual Reference Pages  - ATAN (3)

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atan, atanf, atanl - arc tangent function

CONTENTS

Synopsis
Description

#include <math.h> 



double atan(double x); 



float atanf(float x); 



long double atanl( long double x); 

The atan() function calculates the arc tangent of x; that is the value whose tangent is x.

The atan() function returns the arc tangent in radians and the value is mathematically defined to be between -PI/2 and PI/2 (inclusive).

SVID 3, POSIX, BSD 4.3, ISO 9899. The float and long double variants are C99 requirements.

acos(3), asin(3), atan2(3), cos(3), sin(3), tan(3)

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