ATAN(3G) [FIXME: manual] ATAN(3G)

# NAME

atan - return the arc-tangent of the parameters

# DECLARATION

genType atan(genType y, genType x);

genType atan(genType y_over_x);

# PARAMETERS

y

Specify the numerator of the fraction whose arctangent to return.

x

Specify the denominator of the fraction whose arctangent to return.

y_over_x

Specify the fraction whose arctangent to return.

# DESCRIPTION

atan returns either the angle whose trigonometric arctangent is $y \over x$ or y_over_x, depending on which overload is invoked. In the first overload, the signs of $y$ and $x$ are used to determine the quadrant that the angle lies in. The value returned by atan in this case is in the range $[-\pi,\pi]$. The result is undefined if $x = 0$.

For the second overload, atan returns the angle whose tangent is y_over_x. The value returned in this case is in the range $[-{\pi \over 2 },{\pi \over 2}]$.

# VERSION SUPPORT

 OpenGL Shading Language Version Function Name 1.10 1.20 1.30 1.40 1.50 3.30 4.00 4.10 4.20 4.30 4.40 4.50 atan ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔