undefined reference

[siubo]

This is my C code:
int main(int argc, char **argv)
{
vec_t **x;
PATTERN *pat;
unsigned long num_patfiles, total_num_pats;
pat = (PATTERN *) get_pattern("faem0.test.pds", &num_patfiles,&total_num_pats);
x = extract_patterns(pat, num_patfiles, total_num_pats);
return(0);
}

After I compile it, two messages come out:
1. undefined reference to 'get_pattern(char *, unsigned long *, unsigned long *)'
2. undefined reference to 'extract_pattern(char *, unsigned long *, unsigned long *)'

What is undefined reference? How can I solve this problem?

[Vber]

first of all, use code tags, second, where did you declare those functions? (get_pattern and so on...) the compiler don't recognize this functions, neither me, I'm quite sure they're not ANSI.