makefile question about combining c and cuda code

Accelerated Computing CUDA CUDA Programming and Performance
1

OBJS=main.o ccode.o cudacode.o
COMP=cc -Wall

main: $ (OBJS)
$ (COMP) $ (OBJS) -o main -lm # I also tried to change this (COMP) to nvcc, but still have errors.
main.o: main.c ccode.h cudacode.cuh
$ (COMP) -c main.c
ccode.o: ccode.c ccode.h
$ (COMP) -c ccode.c
cudacode.o: cudacode.cu cudacode.cuh
$ nvcc -c cudacode.cu

I had the following error,

main.c:(.text+0xa3a): undefined reference to `ivrmse’

ivrmse is function defined in cudacode.cu.

Is there any problems in my makefile? Can anybody help me out?

Thanks

2

If I changed all the .c file to .cu and use COMP=nvcc, I have no compiling error.