eduardo@berserker:~$ gcc -Wall -ansi -g lz78.c -o lz78
/tmp/ccgwUYwT.o: In function `log2':/home/eduardo/lz78.c:112: undefined reference to `log'
:/home/eduardo/lz78.c:112: undefined reference to `log'
/tmp/ccgwUYwT.o: In function `codify':/home/eduardo/lz78.c:214: undefined reference to `ceil'
/tmp/ccgwUYwT.o: In function `decodify':/home/eduardo/lz78.c:438: undefined reference to `ceil'
:/home/eduardo/lz78.c:434: undefined reference to `ceil'
collect2: ld returned 1 exit status