How to make Armadillo work on Windows?

Question

I cannot make Armadillo 4.3 work on Windows. The library armadillo/include is included and I run g++ "-LC:\\Armadillo\\BLAS_Lapack" -o1 -o test.exe test.o -llapack -lblas, then I get the following error message:

C:/Armadillo/include/armadillo_bits/blas_wrapper.hpp:183: undefined reference to `wrapper_ddot_'
test.o: In function `ZN4arma4blas4gemvIdEEvPKcPKiS5_PKT_S8_S5_S8_S5_S8_PS6_S5_':
C:/Armadillo/include/armadillo_bits/blas_wrapper.hpp:34: undefined reference to `wrapper_dgemv_'
test.o: In function `ZN4arma4blas4gemmIdEEvPKcS3_PKiS5_S5_PKT_S8_S5_S8_S5_S8_PS6_S5_':
C:/Armadillo/include/armadillo_bits/blas_wrapper.hpp:69: undefined reference to `wrapper_dgemm_'

If I run g++ -o1 -o test.exe test.o -llapack -lblas, I get

c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: cannot find -llapack
c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: cannot find -lblas

I did uncomment the configuration file config.hpp according to the README file.

Does anybody know how to make Armadillo work? (I am using Eclipse CDT.)

Answer 1

It took a while to get this right, but it seems transparent once it works. I will explain step by step. (Make sure you have uncommented the correct lines as directed in the README of the config.hpp file)

The general command for compiling with blas/lapack (using the default provided with armadillo (current version 4.500.0) and does make it faster :)

g++ main.cpp -I C:{ARMADILLO_ROOT}\include -L C:{ARMADILLO_ROOT}\examples\lib_win64 -lblas_win64_MT -llapack_win64_MT

where each of the commands are as follows:

1. g++: GNU G++ Compiler (using MinGW 4.9.1 C++ from equationsolution.com)

2. main.cpp: My main file of the C++ program (I have an abstract and concrete class defining the Levenshtein algorithm)

3. -I C:{ARMADILLO_ROOT}\include: The GCC C++ Compiler Include Path (To include the Armadillo library) where ARMADILLO_ROOT is where you have decompressed and placed your armadillo files

4. -L C:{ARMADILLO_ROOT}\examples\lib_win64: The MinGW C++ Linker Library Link Path (To link the BLAS and LAPACK libraries) I have used the default libs provided with armadillo, I believe and according to the doc you may and should substitute these linear libraries in a production instance)

5. -lblas_win64_MT -llapack_win64_MT: Identify the libraries to be used (name must match, so you cannot put -lblas or -llapack UNLESS your files are named that way - by default in this armadillo version they are named blas_win64_MT lapack_win64_MT (win64 since I am using both a MinGW/C++ 64bit and a 64bit armadillo [they should match])

Following this logic, you may configure eclipse (using eclipse Luna R1 4.4.1 -should be the same procedure on other versions) with the following:

• Right Click the Project and Select "Properties" item in the popup menu
• Under "C/C++ Build" on the left menu Select "Settings"
• Under "GCC C++ Compiler" click on "Includes (-I)" and add the include path C:{ARMADILLO_ROOT}\include (Screenshot1)
• Under "MinGW C++ Linker" click on "Libraries" add each "Libraries (-l)" as named blas_win64_MT lapack_win64_MT. (Screenshot2)
• Under the same "MinGW C++ Linker" click on "Libraries" add a "Library search path (-L)" C:{ARMADILLO_ROOT}\examples\lib_win64
• Click the "Apply" button before pressing "OK"

--Screenshot1

--Screenshot2

Answer 2

It seems to work now! I am using the Lapack and BLAS from the webpage indicated in the Readme file that I compiled myself according to @enhzflep comments.

To link everything properly in Eclipse CDT right click on your project and go to properties, then:

1. Under "C/C++ Build⟼Settings⟼GCC C++ Compiler⟼Command" type: g++ -I"C:\Armadillo\include" (replace with the correct path for your Armadillo folder). Make sure to do this for all Configurations (to be chosen in the drop-down menu at the top).
2. Under "C/C++ Build⟼Settings⟼MinGW C++ Linker⟼Libraries" add lapack and blas to the Libraries.
3. Under"C/C++ General⟼Paths and Symbols⟼GNU C++" add the path tot he include directory of your Armadillo folder C:\Armadillo\include.

It might be that it works with the original Lapack and BLAS files. It did not work for me, because I had only added the path to Armadillo under "C/C++ General⟼Paths and Symbols⟼GNU C++", which I guess only tells the editor what data types and functions to expect and not the compiler.