cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations math/atanl.c -o math/atanl -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lintl -liconv
math/atanl.c:5:35: error: ‘atanl’ undeclared here (not in a function); did you mean ‘atanf’?
    5 | long double (*foo)(long double) = atanl;
      |                                   ^~~~~
      |                                   atanf