cc -pipe -O   -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations math/M_SQRT3.c -o math/M_SQRT3 -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lrt -lcrypt
math/M_SQRT3.c:8:21: error: 'M_SQRT3' undeclared here (not in a function); did you mean 'M_SQRT2'?
 double  const foo = M_SQRT3;
                     ^~~~~~~
                     M_SQRT2