cc -pthread -Wall -Wextra -Werror=implicit-function-declaration complex/catanhl.c -o complex/catanhl -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv complex/catanhl.c:11: warning: ignoring ‘#pragma STDC FENV_ACCESS’ [-Wunknown-pragmas] 11 | #pragma STDC FENV_ACCESS ON complex/catanhl.c: In function ‘test’: complex/catanhl.c:24:38: error: implicit declaration of function ‘catanhl’ [-Wimplicit-function-declaration] 24 | long double complex output = catanhl(input1); | ^~~~~~~ complex/catanhl.c:10:1: note: include ‘’ or provide a declaration of ‘catanhl’ 9 | #include "../basic.h" +++ |+#include 10 | complex/catanhl.c:24:38: warning: incompatible implicit declaration of built-in function ‘catanhl’ [-Wbuiltin-declaration-mismatch] 24 | long double complex output = catanhl(input1); | ^~~~~~~ complex/catanhl.c:24:38: note: include ‘’ or provide a declaration of ‘catanhl’