Linking error of BLAS with CMake - c++

Question

I have the following CMakeLists.txt:
cmake_minimum_required (VERSION 2.6)
project (MTSOS)
# Select flags.
set(CMAKE_C_FLAGS "-std=c99")
# Blas library
find_package( BLAS REQUIRED )
include_directories(${BLAS_INCLUDE_DIR})
add_executable (test_MTSOS test_MTSOS.c barrier_front.c dynamics_front.c
MTSOS.c csparse.c)
# Linking CImg dependencies.
target_link_libraries (test_MTSOS m blas ${BLAS_LIBRARIES})
When I run cmake .. :
-- The C compiler identification is GNU 4.8.2
-- The CXX compiler identification is GNU 4.8.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Looking for dgemm_
-- Looking for dgemm_ - found
-- Looking for include file pthread.h
-- Looking for include file pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- A library with BLAS API found.
-- Configuring done
-- Generating done
-- Build files have been written to: /home/jabuntu14/Desktop/MTSOS/build
However, when I try to compile with make:
Scanning dependencies of target test_MTSOS
[ 20%] Building C object CMakeFiles/test_MTSOS.dir/test_MTSOS.c.o
[ 40%] Building C object CMakeFiles/test_MTSOS.dir/barrier_front.c.o
/home/jabuntu14/Desktop/MTSOS/barrier_front.c: In function ‘so_barrier’:
/home/jabuntu14/Desktop/MTSOS/barrier_front.c:83:25: warning: implicit declaration of function ‘dsyr’ [-Wimplicit-function-declaration]
dsyr(uplo, &u_size, &alpha, &Df[i*U_size], &one, A, &u_size);
^
[ 60%] Building C object CMakeFiles/test_MTSOS.dir/dynamics_front.c.o
[ 80%] Building C object CMakeFiles/test_MTSOS.dir/MTSOS.c.o
/home/jabuntu14/Desktop/MTSOS/MTSOS.c: In function ‘so_MakeA’:
/home/jabuntu14/Desktop/MTSOS/MTSOS.c:1561:13: warning: implicit declaration of function ‘dgemv’ [-Wimplicit-function-declaration]
dgemv(chn, &m_m, &n_m, &one, &M_dynamics[i*State_size*State_size], &m_m, &S_prime[i*State_size], &p_m, &zero, datam, &p_m);
^
[100%] Building C object CMakeFiles/test_MTSOS.dir/csparse.c.o
Linking C executable test_MTSOS
CMakeFiles/test_MTSOS.dir/barrier_front.c.o: In function `so_barrier':
barrier_front.c:(.text+0x4a7): undefined reference to `dsyr'
CMakeFiles/test_MTSOS.dir/MTSOS.c.o: In function `so_MakeA':
MTSOS.c:(.text+0x5e41): undefined reference to `dgemv'
MTSOS.c:(.text+0x5ee4): undefined reference to `dgemv'
MTSOS.c:(.text+0x5f87): undefined reference to `dgemv'
collect2: error: ld returned 1 exit status
make[2]: *** [test_MTSOS] Error 1
make[1]: *** [CMakeFiles/test_MTSOS.dir/all] Error 2
make: *** [all] Error 2
So I am having a linking problem but I cannot figure out why. Any help is welcome. Thanks!!
NOTE: Working under Ubuntu 14.04 with GCC. In the .c files I have included #include "cblas.h" as I saw in other websites.
EDIT: running make VERBOSE=1 the output is:
jabuntu14#ubuntu:~/Desktop/MTSOS/build$ make VERBOSE=1
/usr/bin/cmake -H/home/jabuntu14/Desktop/MTSOS -B/home/jabuntu14/Desktop/MTSOS/build --check-build-system CMakeFiles/Makefile.cmake 0
/usr/bin/cmake -E cmake_progress_start /home/jabuntu14/Desktop/MTSOS/build/CMakeFiles /home/jabuntu14/Desktop/MTSOS/build/CMakeFiles/progress.marks
make -f CMakeFiles/Makefile2 all
make[1]: Entering directory `/home/jabuntu14/Desktop/MTSOS/build'
make -f CMakeFiles/test_MTSOS.dir/build.make CMakeFiles/test_MTSOS.dir/depend
make[2]: Entering directory `/home/jabuntu14/Desktop/MTSOS/build'
cd /home/jabuntu14/Desktop/MTSOS/build && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/jabuntu14/Desktop/MTSOS /home/jabuntu14/Desktop/MTSOS /home/jabuntu14/Desktop/MTSOS/build /home/jabuntu14/Desktop/MTSOS/build /home/jabuntu14/Desktop/MTSOS/build/CMakeFiles/test_MTSOS.dir/DependInfo.cmake --color=
make[2]: Leaving directory `/home/jabuntu14/Desktop/MTSOS/build'
make -f CMakeFiles/test_MTSOS.dir/build.make CMakeFiles/test_MTSOS.dir/build
make[2]: Entering directory `/home/jabuntu14/Desktop/MTSOS/build'
Linking C executable test_MTSOS
/usr/bin/cmake -E cmake_link_script CMakeFiles/test_MTSOS.dir/link.txt --verbose=1
/usr/bin/cc -std=c99 CMakeFiles/test_MTSOS.dir/test_MTSOS.c.o CMakeFiles/test_MTSOS.dir/barrier_front.c.o CMakeFiles/test_MTSOS.dir/dynamics_front.c.o CMakeFiles/test_MTSOS.dir/MTSOS.c.o CMakeFiles/test_MTSOS.dir/csparse.c.o -o test_MTSOS -rdynamic -lm -lblas -lf77blas -latlas
CMakeFiles/test_MTSOS.dir/barrier_front.c.o: In function `so_barrier':
barrier_front.c:(.text+0x4a7): undefined reference to `dsyr'
CMakeFiles/test_MTSOS.dir/MTSOS.c.o: In function `so_MakeA':
MTSOS.c:(.text+0x5e41): undefined reference to `dgemv'
MTSOS.c:(.text+0x5ee4): undefined reference to `dgemv'
MTSOS.c:(.text+0x5f87): undefined reference to `dgemv'
collect2: error: ld returned 1 exit status
make[2]: *** [test_MTSOS] Error 1
make[2]: Leaving directory `/home/jabuntu14/Desktop/MTSOS/build'
make[1]: *** [CMakeFiles/test_MTSOS.dir/all] Error 2
make[1]: Leaving directory `/home/jabuntu14/Desktop/MTSOS/build'
make: *** [all] Error 2

Answer 1

The functions in standard blas libraries are
dgemv_
Instead of
dgemv
As shown in your error, notice the trailing underscore.
So you probably have something in your code calling dgemv() instead of dgemv_(), change that and then you should be fine.
(I had the same issue where the code I was using had some like #define dgemv_ dgemv)