CACOS(3) Linux Programmer's Manual CACOS(3)

NAME
       cacos, cacosf, cacosl - complex arc cosine

SYNOPSIS
       #include 

       double complex cacos(double complex z);
       float complex cacosf(float complex z);
       long double complex cacosl(long double complex z);

       Link with -lm.

DESCRIPTION
       The  cacos()  function  calculates  the  complex  arc  cosine of z.  If
       y = cacos(z), then z = ccos(y).  The real part of y is  chosen  in  the
       interval [0,pi].

       One has:

           cacos(z) = -i * clog(z + i * csqrt(1 - z * z))

VERSIONS
       These functions first appeared in glibc in version 2.1.

ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).

       ┌─────────────────────────────┬───────────────┬─────────┐
       │Interface                    │ Attribute     │ Value   │
       ├─────────────────────────────┼───────────────┼─────────┤
       │cacos(), cacosf(), cacosl()  │ Thread safety │ MT-Safe │
       └─────────────────────────────┴───────────────┴─────────┘
CONFORMING TO
       C99.

EXAMPLE
       /* Link with "-lm" */

       #include 
       #include 
       #include 
       #include 

       int
       main(int argc, char *argv[])
       {
           double complex z, c, f;
           double complex i = I;

           if (argc != 3) {
               fprintf(stderr, "Usage: %s  \n", argv[0]);
               exit(EXITFAILURE);
           }

           z = atof(argv[1]) + atof(argv[2]) * I;

           c = cacos(z);

           printf("cacos() = %6.3f %6.3f*i\n", creal(c), cimag(c));

           f = -i * clog(z + i * csqrt(1 - z * z));

           printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f));

           exit(EXITSUCCESS);
       }

SEE ALSO
       ccos(3), clog(3), complex(7)

COLOPHON
       This page is part of release 3.53 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



                                  2011-09-15                          CACOS(3)