ACOS (man3p)
acos, acosf, acosl — arc cosine functions
acos, acosf, acosl — arc cosine functions
fegetenv, fesetenv — get and set current floating-point environment
timer_getoverrun, timer_gettime, timer_settime — per-process timers
hypot, hypotf, hypotl — Euclidean distance function
aio_return — retrieve return status of an asynchronous I/O operation
getprotobyname, getprotobynumber, getprotent — network protocol database functions
trunc, truncf, truncl — round to truncated integer value
fgets — get a string from a stream
strncasecmp, strncasecmp_l — case-insensitive string comparisons
send — send a message on a socket