# naginterfaces.library.specfun.arccos¶

naginterfaces.library.specfun.arccos(x)[source]

arccos returns the value of the inverse circular cosine, ; the result is in the principal range .

For full information please refer to the NAG Library document for s09ab

https://www.nag.com/numeric/nl/nagdoc_28.5/flhtml/s/s09abf.html

Parameters
xfloat

The argument of the function.

Returns
acxfloat

The value of the inverse circular cosine, .

Raises
NagValueError
(errno )

On entry, .

Constraint: .

Notes

No equivalent traditional C interface for this routine exists in the NAG Library.

arccos calculates an approximate value for the inverse circular cosine, . It is based on the Chebyshev expansion

where .

For .

For .

For .

For is undefined and the function fails.

References

NIST Digital Library of Mathematical Functions