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ATAN(3)                  BSD Library Functions Manual                  ATAN(3)

NAME
     atan -- arc tangent function of one variable

SYNOPSIS
     #include <math.h>

     double
     atan(double x);

     long double
     atanl(long double x);

     float
     atanf(float x);

DESCRIPTION
     The atan() function computes the principal value of the arc tangent of x.  The result is in the range
     [-pi/2, +pi/2].

SPECIAL VALUES
     atan(+-_) returns +-0.

     atan(+-infinity) returns +-pi/2

VECTOR OPERATIONS
     If you need to apply the atan() function to SIMD vectors or arrays, using the following functions pro-vided provided
     vided by the Accelerate.framework may give significantly better performance:

     #include <Accelerate/Accelerate.h>

     vFloat vatanf(vFloat x);
     void vvatanf(float *y, const float *x, const int *n);
     void vvatan(double *y, const double *x, const int *n);

SEE ALSO
     acos(3), asin(3), atan2(3), cos(3), cosh(3), sin(3), sinh(3), tan(3), tanh(3), math(3) The atan() func-tion function
     tion conforms to ISO/IEC 9899:2011.

BSD                            December 11, 2006                           BSD