Compiling: undefined reference to - c

Question

I'm struggling with compiling multiple files into a common program. I'm getting an error:
undefined reference to 'pi'
Here's the skeleton of my code and Makefile. What am I doing wrong? Thanks!
File: calcPi.c
#include <stdlib.h>
#include <stdio.h>
#include <sched.h>
#include <string.h>
#include "pi.h"
int main(int argc, char* argv[]) {
long iterations = 1000000;
int policy = 2;
int numChildren = 3;
pi(iterations, policy, numChildren);
return 0;
}
File: pi.h
void pi(long iterations, int policy, int numChildren);
File: pi.c
#include "pi.h"
void pi(long iterations, int policy, int numChildren) {
//lots of code here
}
I'm compiling this using a Makefile:
CC = gcc
CFLAGS = -c -g -Wall -Wextra
LFLAGS = -g -Wall -Wextra
all: calcPi pi
calcPi: calcPi.o
$(CC) $(LFLAGS) $^ -o $# -lm
pi: pi.o
$(CC) $(LFLAGS) $^ -o $# -lm
calcPi.o: calcPi.c
$(CC) $(CFLAGS) $<
pi.o: pi.c
$(CC) $(CFLAGS) $<
clean:
rm -f pi calcPi
rm -f *.o
rm -f *~
EDIT: In response to the request for the entire error message:
In function 'main'"
calcPi.c:55: undefined reference to 'pi'
collect2: error: ld returned 1 exit status
make: * [calcPi.o] error 1

Answer 1

First of all, is pi really supposed to be a separate application?
You're referring the pi() function from calcPi, but it's only been compiled into pi.o, so you need to add it as a dependency.
What I think you want to do, is to create calcPi using the calcPi.o and pi.o object files.
CC = gcc
CFLAGS = -c -g -Wall -Wextra
LFLAGS = -g -Wall -Wextra
all: calcPi
calcPi: calcPi.o pi.o
$(CC) $(LFLAGS) $^ -o $# -lm
calcPi.o: calcPi.c
$(CC) $(CFLAGS) $<
pi.o: pi.c
$(CC) $(CFLAGS) $<
clean:
rm -f calc
rm -f *.o
rm -f *~