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ATAN(3)
ATAN(3) FreeBSD Library Functions Manual ATAN(3)

NAME

atan, atanf, atanlarc tangent functions of one variable

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include < math.h>

double
atan( double x);

float
atanf( float x);

long double
atanl( long double x);

DESCRIPTION

The atan(), atanf(), and atanl() functions compute the principal value of the arc tangent of x.

RETURN VALUES

These functions return the arc tangent in the range [-pi/2, +pi/2] radians.

STANDARDS

The atan(), atanf(), and atanl() functions conform to ISO/IEC 9899:1999 (“ISO C99”).
July 31, 2008 FreeBSD