Returns the arc cosine of its argument.

    Format

      #include  <math.h>

      double acos  (double x);

      float acosf  (float x); (Integrity servers, Alpha)

      long double acosl  (long double x); (Integrity servers, Alpha)

      double acosd  (double x); (Integrity servers, Alpha)

      float acosdf  (float x); (Integrity servers, Alpha)

      long double acosdl  (long double x);

                          (Integrity servers, Alpha)