complex cosine function
Math library (libm, -lm)
These functions calculate the complex cosine of z.
The complex cosine function is defined as:
ccos(z) = (exp(i * z) + exp(-i * z)) / 2
For an explanation of the terms used in this section, see attributes(7).
C11, POSIX.1-2008.
glibc 2.1. C99, POSIX.1-2001.