cc -pipe -O   -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations math/M_SQRT1_3.c -o math/M_SQRT1_3 -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lrt -lcrypt
math/M_SQRT1_3.c:8:21: error: 'M_SQRT1_3' undeclared here (not in a function); did you mean 'M_SQRT1_2'?
 double  const foo = M_SQRT1_3;
                     ^~~~~~~~~
                     M_SQRT1_2