atan - return the arc-tangent of the parameters

       Copyright © 2011-2014 Khronos Group

[FIXME: source]                                    11/18/2024                                           ATAN(3G)

genTypeatan(genTypey,genTypex);genTypeatan(genTypey_over_x);

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 $[-{\pi \over 2 },{\pi \over 2}]$.

       atan - return the arc-tangent of the 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.

sin(), cos(), tan()

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       │          │        OpenGLShadingLanguageVersion                                            │
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       │ Function │ 1.10 │ 1.20 │ 1.30 │ 1.40 │ 1.50 │ 3.30 │ 4.00 │ 4.10 │ 4.20 │ 4.30 │ 4.40 │ 4.50 │
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       ├──────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┤
       │ atan     │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │
       └──────────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┘