commandline session
$cat main.c #include<stdio.h> #include<math.h> int main(void) { int i=0; float y; printf("n The Geek Stuff [%d]n", i); y=sinf(2.5); printf("%fn",y); return 0; } $gcc -ansi main.c /tmp/ccBNR3rx.o: In function `main': main.c:(.text+0x3c): undefined reference to `sinf' collect2: error: ld returned 1 exit status $gcc main.c $