undefined reference to `cvGetOptimalDFTSize' - c++

Question

I am working with Opencv-2.1 on arm-linux. I am using arm-linux-g++ compiler. I ran in to a strange error during linking. Before talking about the error, I will post my make commands
CC = arm-linux-g++
COMPILEFLAGS = -Wall -fPIC -c -O2 -I./
OUT_DLL = libLensFinder.so
DLL_FLAGS = -shared -o
OBJS = SegmentRegions.o
OBJS2 = EdgeDetection.o
OBJS3 = AnalyseRegions.o
OBJS4 = global.o
LINK_FLAGS = -L./ -lLensFinder
LINK_FLAGS_2 = -L./ -lTwoX
INCPATH = -I/home/zwang/ravi/opencv_include21/opencv/ -I.
all :
$(CC) $(COMPILEFLAGS) $(INCPATH) global.cpp -o global.o
$(CC) $(COMPILEFLAGS) $(INCPATH) EdgeDetection.cpp -o EdgeDetection.o
$(CC) $(COMPILEFLAGS) $(INCPATH) SegmentRegions.cpp -o SegmentRegions.o
$(CC) $(COMPILEFLAGS) $(INCPATH) AnalyseRegions.cpp -o AnalyseRegions.o
$(CC) $(OBJS) $(OBJS2) $(OBJS3) $(OBJS4) $(DLL_FLAGS) ./$(OUT_DLL) -L/home/zwang/ravi/opencv_include21/lib -lcvaux -lcxcore -lhighgui -lcv -lml -lcxts -lrt
$(CC) $(COMPILEFLAGS) $(INCPATH) sample.cpp
#$(CC) $(LINK_FLAGS) sample.o -o sample
$(CC) $(LINK_FLAGS) $(LINK_FLAGS_2) sample.o -o sample
Everything works fine till the end. During the last command i.e., while creating executable file I am getting the following error.
arm-linux-g++ -L./ -lLensFinder -L./ -lTwoX sample.o -o sample
.//libLensFinder.so: undefined reference to `spotrs_'
.//libLensFinder.so: undefined reference to `cvGetOptimalDFTSize'
.//libLensFinder.so: undefined reference to `dgels_'
.//libLensFinder.so: undefined reference to `dgelsd_'
.//libLensFinder.so: undefined reference to `dgesdd_'
.//libLensFinder.so: undefined reference to `cvMulSpectrums'
.//libLensFinder.so: undefined reference to `sgesdd_'
.//libLensFinder.so: undefined reference to `sgetri_'
.//libLensFinder.so: undefined reference to `cvDFT'
.//libLensFinder.so: undefined reference to `dgesv_'
.//libLensFinder.so: undefined reference to `dgetrf_'
.//libLensFinder.so: undefined reference to `dsyevr_'
.//libLensFinder.so: undefined reference to `sgels_'
.//libLensFinder.so: undefined reference to `spotrf_'
.//libLensFinder.so: undefined reference to `sgetrf_'
.//libLensFinder.so: undefined reference to `dpotrf_'
.//libLensFinder.so: undefined reference to `dpotri_'
.//libLensFinder.so: undefined reference to `sgesv_'
.//libLensFinder.so: undefined reference to `ssyevr_'
.//libLensFinder.so: undefined reference to `dpotrs_'
.//libLensFinder.so: undefined reference to `sgelsd_'
.//libLensFinder.so: undefined reference to `spotri_'
.//libLensFinder.so: undefined reference to `dgetri_'
collect2: ld returned 1 exit status
make: *** [all] Error 1
Two of the undefined references are cvMulSpectrums' andcvGetOptimalDFTSize', which I guess is due to opencv. And I have no clue on other undefined reference. I think I have linked every library. But still can't understand how to solve this. Any suggestions? FYI, the code is working on visual studio.

Answer 1

Those symbols are defined in the libopencv_core library file.
Notice how the command arm-linux-g++ -L./ -lLensFinder -L./ -lTwoX sample.o -o sample doesn't link sample with any opencv library, so it makes sense that the linking process complains about it.
You probably should adjust your build to do something like:
arm-linux-g++ sample.o -o sample -L./ -lLensFinder -L./ -lTwoX -L/home/zwang/ravi/opencv_include21/lib -lcvaux -lcxcore -lhighgui -lcv -lml -lcxts -lrt