Manual Pages for UNIX Operating System command usage for man atan2l

Mathematical Library Functions                          atan2(3M)



NAME
     atan2, atan2f, atan2l - arc tangent function

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

     double atan2(double y, double x);


     float atan2f(float y, float x);


     long double atan2l(long double y, long double x);


DESCRIPTION
     These functions compute  the  principal  value  of  the  arc
     tangent  of y/x, using the signs of both arguments to deter-
     mine the quadrant of the return value.

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


     If y is +_0 and x is < 0, +_pi is returned.


     If y is +_0 and x is > 0, +_0 is returned.


     If y is < 0 and x is +_0, -pi/2 is returned.


     If y is > 0 and x is +_0, pi/2 is returned.


     If x is 0, a pole error does not occur.


     If either x or y is NaN, a NaN is returned.


     If y is +_0 and x is -0, +_pi is returned.


     If y is +_0 and x is +0, +_0 is returned.


     For finite values of +_y > 0, if x is -Inf,  +_pi is returned.




SunOS 5.11          Last change: 12 Jul 2006                    1






Mathematical Library Functions                          atan2(3M)



     For finite values of +_y > 0, if x is +Inf,  +_0 is returned.


     For finite values of x, if y is +_Inf, +_pi/2 is returned.


     If y is +_Inf and x is -Inf, +_3pi/4 is returned.


     If y is +_Inf and x is +Inf, +_pi/4 is returned.


     If both arguments are 0, a domain error does not occur.

ERRORS
     No errors are defined.

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



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|
    | Standard                    | See standards(5).           |
    |_____________________________|_____________________________|


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


















SunOS 5.11          Last change: 12 Jul 2006                    2