Mathematical Library Functions                           atan(3M)



NAME
     atan, atanf, atanl - arc tangent function

SYNOPSIS
     c99 [ flag... ] file... -lm [ library... ]
     #include 

     double atan(double x);


     float atanf(float x);


     long double atanl(long double x);


DESCRIPTION
     These functions compute  the  principal  value  of  the  arc
     tangent of x.

RETURN VALUES
     Upon successful completion, these functions return  the  arc
     tangent of x in the range [-pi/2,pi/2] radians.


     If x is NaN, NaN is returned.


     If x is ]0, x is returned.


     If x is ]Inf, ]pi/2 is returned.

ERORS
     No errors are defined.

ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:
















SunOS 5.11          Last change: 12 Jul 2006                    1






Mathematical Library Functions                           atan(3M)



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Standard                    
    
     MT-Level                     MT-Safe                     
    


SEE ALSO
     atan2(3M), isnan(3M), math.h(3HEAD), tan(3M), attributes(5),
     standards(5)











































SunOS 5.11          Last change: 12 Jul 2006                    2