gcc tip note
link lib
for example link math lib
gcc main.c -lm
man pow
POW(3) Linux Programmer's Manual POW(3)
NAME
pow, powf, powl - power functions
SYNOPSIS
#include <math.h>
double pow(double x, double y);
float powf(float x, float y);
long double powl(long double x, long double y);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
powf(), powl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
DESCRIPTION
These functions return the value of x raised to the power of y.