Function: acos

acos is a function defined in floatfns.c.

Signature

(acos ARG)

Documentation

Return the inverse cosine of ARG.

Other relevant functions are documented in the number group.

View in manual

Probably introduced at or before Emacs version 24.3.

Shortdoc

;; number
(acos float-pi)
    => 0.0e+NaN

Source Code

// Defined in /usr/src/emacs/src/floatfns.c
{
  double d = extract_float (arg);
  d = acos (d);
  return make_float (d);
}