```
gentype
```
| gentype `)` |

```
gentype
```
| gentype `)` |

```
gentype
```
| gentype x`)` |

`acos`

is the arc cosine function.

`acosh`

is the inverse hyperbolic cosine function.

`acospi`

computes `acos`

(`x`

) / pi.

The vector versions of the math functions operate component-wise. The description is per-component.

The built-in math functions are not affected by the prevailing rounding mode in the calling environment, and always return the same value as they would if called with the round to nearest even rounding mode.

The `acos`

, `acosh`

, and `acospi`

built-in math functions take scalar or vector arguments. The generic type name gentype is used to indicate that the function can take float, float2, float4, float8, or float16 as the type for the arguments. For any specific
use of these function, the actual type has to be the same for all arguments and the return type.

If extended with cl_khr_fp64, generic type name gentype may indicate double and double{2|4|8|16} as arguments and return values. If extended with cl_khr_fp16, generic type name gentype may indicate half and half{2|4|8|16} as arguments and return values.

Copyright © 2007-2009 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be included
in all copies or substantial portions of the Materials.