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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
Javi
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  • Please run with `make VERBOSE=1` and show us the full `ld` command used. – Peter Petrik Sep 23 '14 at 09:24
  • possible duplicate of [What is an undefined reference/unresolved external symbol error and how do I fix it?](http://stackoverflow.com/questions/12573816/what-is-an-undefined-reference-unresolved-external-symbol-error-and-how-do-i-fix) – Peter Petrik Sep 23 '14 at 09:26
  • It is not a duplicate of that post, it is just an special case. I do not have this error with any other library. – Javi Sep 23 '14 at 17:27
  • @Peter I have made an edit to the post addind the make VERBOSE=1 info. I do not know exactly what do you mean with the full ld command used. Thank you for your help. – Javi Sep 23 '14 at 17:36
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    If I remember correctly, you need to link against cblas and not blas libraries, see [here](http://www.math.utah.edu/software/lapack.html). – Bort Sep 23 '14 at 17:47
  • @Bort thank you, but it gives the same error. I've changed blas by cblas in the CMakeLists.txt and nothing changes. Note: I am not using LAPACK, just BLAS. – Javi Sep 23 '14 at 17:53
  • Could you ever solve this problem? – ar2015 Nov 03 '17 at 00:14
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    @ar2015 honestly, I do not remember :S – Javi Nov 03 '17 at 05:04

1 Answers1

0

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)

Shawn
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