See(C) Code

lets consider simple program below this program will compile but linker fails to find definition of cos and sin functions #include<stdio.h> #include<math.h> #include <stdlib.h> #define PI 3.142 int main() {  double sinval, cosval;  int x=2;  sinval = sin(PI/x);  cosval = cos(PI/x);  printf("sin and cos of PI/x  is %lf %lf\n", sinval, cosval);  return 0; } followings link errors we will hit, since linker can't able to resolve the definition of cos() and sin() shiv@ubuntu:~$ gcc mat1.c /tmp/ccHOvWsZ.o: In function `main': mat1.c:(.text+0x2a): undefined reference to `sin' mat1.c:(.text+0x4b): undefined reference to `cos' collect2: ld returned 1 exit status so to fix the above issue we need to link the required library, here cos() and sin() are present in the math library so we need to link math library with the program as follows gcc  mat1.c -lm -lm will link the math library with above program so program build properly, so as li