Matlab mex code not compiling using a Makefile - Undefined Reference - matlab

Question

I have a matlab mex extension which I want to compile using a Makefile. The Linker does not seem to find the mex libraries. Here is the Makefile:
MEXSUFFIX = mexa64
IX = mexa64
MATLABHOME = /usr/local/MATLAB/R2013b
MEX = g++
MEXCXX = echo
CXX = g++
CFLAGS = -fPIC -pthread -DMATLAB_MEX_FILE -ansi -D_GNU_SOURCE -fno-omit-frame-pointer -pthread -O3 -DNDEBUG
LIBS = -lm
INCLUDE = -I$(MATLABHOME)/extern/include -Icommon
#g++
MEXFLAGS = -shared -Wl,--no-undefined -Wl,-rpath-link,$(MATLABHOME)/bin/glnxa64 -L$(MATLABHOME)/bin/glnxa64 -lmx -lmex -lmat -lm
PROJECTS = residualfm
MEXDIR = ..
all: $(PROJECTS)
residualfm: residualfm/functions.o
$(MEX) $(MEXFLAGS) $(LIBS) -o $(MEXDIR)/$#.$(MEXSUFFIX) $^
.cpp.o:
$(CXX) -c -o $# $< $(CFLAGS) $(INCLUDE)
clean:
rm -f common/*.o
for proj in $(PROJECTS); do \
rm -f $$proj/*.o; \
rm -f $(MEXDIR)/$$proj.$(MEXSUFFIX); \
done
and here my filestructure:
$ ls *
Makefile mex.kdev4 sfr_mex.sln sfr_mex.suo sfr_mex.v11.suo
residualfm:
DllMain.cpp residualfm_variant.def stdafx.h
functions.cpp residualfm_variant.vcxproj timing.cpp
functions.o residualfm_variant.vcxproj.user
maxflow_classic_boykov stdafx.cpp
Here is the error:
$ make
g++ -shared -Wl,--no-undefined -Wl,-rpath-link,/usr/local/MATLAB/R2013b/bin/glnxa64 -L/usr/local/MATLAB/R2013b/bin/glnxa64 -lmx -lmex -lmat -lm -lm -o ../residualfm.mexa64 residualfm/functions.o
residualfm/functions.o: In function `mexFunction':
functions.cpp:(.text+0x27b): undefined reference to `mexErrMsgTxt'
functions.cpp:(.text+0x2a0): undefined reference to `mexErrMsgTxt'
functions.cpp:(.text+0x2c7): undefined reference to `mxGetClassID'
functions.cpp:(.text+0x2e5): undefined reference to `mexErrMsgTxt'
functions.cpp:(.text+0x301): undefined reference to `mxGetNumberOfDimensions'
functions.cpp:(.text+0x320): undefined reference to `mexErrMsgTxt'
functions.cpp:(.text+0x341): undefined reference to `mxGetData'
functions.cpp:(.text+0x350): undefined reference to `mxGetDimensions'
functions.cpp:(.text+0x371): undefined reference to `mxGetNumberOfElements'
functions.cpp:(.text+0x390): undefined reference to `mexErrMsgTxt'
functions.cpp:(.text+0x3aa): undefined reference to `mxGetScalar'
functions.cpp:(.text+0x3c5): undefined reference to `mxGetNumberOfElements'
functions.cpp:(.text+0x3e4): undefined reference to `mexErrMsgTxt'
functions.cpp:(.text+0x3fe): undefined reference to `mxGetScalar'
functions.cpp:(.text+0x4f5): undefined reference to `mexErrMsgTxt'
functions.cpp:(.text+0xdd3): undefined reference to `mxCreateNumericArray'
functions.cpp:(.text+0xdde): undefined reference to `mxGetData'
functions.cpp:(.text+0xefe): undefined reference to `mxGetScalar'
functions.cpp:(.text+0xf9d): undefined reference to `mxCreateNumericArray'
functions.cpp:(.text+0xfa8): undefined reference to `mxGetData'
functions.cpp:(.text+0x11dc): undefined reference to `mxCreateSparse'
functions.cpp:(.text+0x11e7): undefined reference to `mxGetJc'
functions.cpp:(.text+0x11f2): undefined reference to `mxGetIr'
functions.cpp:(.text+0x11fd): undefined reference to `mxGetPr'
residualfm/functions.o: In function `visit_backwards(Node*, Node*, double*, int)':
functions.cpp:(.text+0x232): undefined reference to `mexErrMsgTxt'
collect2: error: ld returned 1 exit status
make: *** [residualfm] Error 1
Compiling from matlab using mex functions.cpp works fine
edit:
Thanks for the hints!
Solved (but not understood):
Changing the order in residualfm: residualfm/functions.o from:
$(MEX) $(MEXFLAGS) $(LIBS) -o $(MEXDIR)/$#.$(MEXSUFFIX) $^
to
$(MEX) -o $(MEXDIR)/$#.$(MEXSUFFIX) $^ $() $(MEXFLAGS) $(LIBS)
solved the problem. Can someone explain this?

Answer 1

(Solved in the comments and edits. See Question with no answers, but issue solved in the comments (or extended in chat) )
#Amro wrote:
Linked libraries must come after the file being compiled in the command-line
The OP wrote:
Changing the order in residualfm: residualfm/functions.o from:
$(MEX) $(MEXFLAGS) $(LIBS) -o $(MEXDIR)/$#.$(MEXSUFFIX) $^
to
$(MEX) -o $(MEXDIR)/$#.$(MEXSUFFIX) $^ $() $(MEXFLAGS) $(LIBS)
solved the problem.