Am working a c++ project that uses the armadillo library to compute some linear algebra equations.
To do this, i have downloaded armadillo package and installed successfully and my code/project works good.But now, i want to remove the the installed library(armadillo) and i want to access from a folder that contains the full package of armadillo using a file path.
...is it possible to do so, please.(accessing using file path). if i am in a right way, can i have a simple illustration .
thank u for your time to help me.
Assuming that you have Linux or Mac OS X and a recent version of armadillo unpacked in /home/kahsay/, you can use the following command:
g++ myprog.cpp -o myprog -O2 -I /home/kahsay/armadillo-4.400.2/include -DARMA_USE_LAPACK -DARMA_USE_BLAS -DARMA_DONT_USE_WRAPPER -llapack -lblas
Under Mac OS X you may need to use -framework Accelerate instead of -llapack -lblas
You can tell the compiler where it should look for the Armadillo headers like g++ -I~/project/embedded_armadillo_headers .... To use Armadillo it suffices to provide the header files, you do not need to link against an Armadillo library itself, just make sure to link against BLAS and LAPACK.
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I'm trying to compile a program i made using SDL2 to work on others computers (or testing VM in this case).
I've been compiling it with what i think are the correct flags, e.g. g++ main.cpp -o main -lSDL2, however when i try executing it on another Ubuntu installation i get this error.
error while loading shared libraries: libSDL2-2.0.so.0: cannot open shared object file: No such file or directory
From my understanding it's not a problem in my compiling but with how i expect it to work on another Linux installation; I've cross-compiled (using mingw32) and tested it (using a freshly installed VM) on Windows adding the correct dlls with the exe (seems to work fine) and I was expecting for it to work in a similar fashion.
What's the standard in this cases? Should i write a setup scripts to install the library dependencies on the target machine? Is there another way I'm not aware of? I've never released an application for Linux (nor Windows) and I'm struggling to find the resources to do things "the right way".
Thanks for everyone suggestions, I ended up settling for the easy way, compiling the "easy to install" libraries dynamically e.g.-lSDL2 and the others statically (checked the licenses and it should be fine) like so:
g++ main.cpp -o main -Wl,-Bdynamic -lSDL2 -lSDL2_image -lSDL2_ttf -Wl,-Bstatic -lSDL2_gfx -static-libgcc -static-libstdc++
I'll put in my documentation how to install the required SDL2 libraries.
I am not sure how familiar you are with pkg-config, but the output for sdl2 is this:
-D_REENTRANT -I/usr/include/SDL2 -lSDL2
This was found from running this:
pkg-config --cflags --libs sdl2
Basically, you need to point to where SDL2 is located BEFORE you actually link to it.
The tool pkg-config is designed to tell you the information you need when you want to link to a package in Linux. You were linking with the library, but you forgot to tell GCC where the library is located.
If you want to compile you code, try this:
g++ main.cpp -o runme `pkg-config --cflags --libs sdl2`
This will automatically grab all of the flags that you need to compile with SDL2 included.
Oh, and you should note, ORDER MATTERS WHEN ADDING FLAGS AND LIBRARIES!!!
There are many questions on SO where the order of compiler options caused all of the problems. Do not be like those people. I suggest you search SO for more info on that.
I'm working on a project on a Raspberry Pi 2 Model B. I started coding and compiling directly on the Pi and now I want to work on a Windows 7 PC. I already installed the SysGCC Cross-Compiler and managed to compile a simple Hello-World program.
Problem is, for my Project i use curl and jsoncpp. Natively on the Raspberry i have no problems compiling it, but the cross-compiler on Windows gives me following error:
c:/sysgcc/raspberry/bin/../lib/gcc/arm-linux-gnueabihf/6/../../../../arm-linux-gnueabihf/bin/ld.exe: cannot find -lcurl
c:/sysgcc/raspberry/bin/../lib/gcc/arm-linux-gnueabihf/6/../../../../arm-linux-gnueabihf/bin/ld.exe: cannot find -ljsoncpp
I don't use a makefile or so because i never really worked with that and on the raspi it just worked fine with this command:
g++ ../src/rpi/main.cpp ../src/rpi/connection.cpp ../src/rpi/jsonparser.cpp ../src/rpi/idchecker.cpp ../src/rpi/eventoperator.cpp -o ../bin/main -lcurl -ljsoncpp
On the Windows system i tried it with a command like this:
arm-linux-gnueabihf-g++.exe -std=c++11 ../src/rpi/main.cpp ../src/rpi/connection.cpp ../src/rpi/jsonparser.cpp ../src/rpi/idchecker.cpp ../src/rpi/eventoperator.cpp -o ../bin/main -L"C:/SysGCC/raspberry/arm-linux-gnueabihf/sysroot/usr/include/jsoncpp/json/" -L"C:/SysGCC/raspberry/arm-linux-gnueabihf/sysroot/usr/include/arm-linux-gnueabihf/curl/" -lcurl -ljsoncpp
So i read that i have to tell the compiler/linker where the libraries are, but i don't really understand why since it works perfectly without the -L flag on the Raspi. I think i put the libraries in the same folder as on the Raspi, so i don't understand why they are not found. I hope someone can help me ore give me some short basic explanation on how this stuff works, cause i don't find any working tutorial or other helpful questions for my problem.
On raspberry-pi the libraries are most likely to be linked from system directory like /usr/lib or /usr/local/lib. On Windows, you need to specify the correct path(s) with -L flag.
I wrote a C++ shared library that uses Intel MKL for BLAS operations, and it threads beautifully, using all 12 cores of the machine. I am now trying to use RCpp to call a function from my library, and I am finding that it is single threaded. As in, for the same data, when the same function is called from C++, it uses all 12 cores very quickly, whereas when Rcpp calls it, it is single threaded and takes much longer (but the results are consistent).
Intel MKL is dynamically linked to my library thusly:
Makefile:
LIBRARIES=-lpthread -Wl,--no-as-needed -L<directory>bin -liomp5 -L<bin_directory> -lmkl_mc3 -lmkl_intel_lp64 -lmkl_gnu_thread -ldl -lmkl_core -lm -DMKL_ILP64 -fopenmp
LFLAGS=-O3 -I/opt/intel/composer_xe_2015/mkl/include -std=c++0x -m64
#Compiles the shared library
g++ -fPIC -shared <cpp files> -oliblibrary.so $(LIBRARIES) -O3 -I/opt/intel/composer_xe_2015/mkl/include -std=c++0x -m64
#Compile a controller for R, so that it can be loaded as dyn.load()
PKG_LIBS='`Rscript -e "Rcpp:::LdFlags() $(LIBRARIES) $(LFLAGS)"`' \
PKG_CXXFLAGS='`Rscript -e "Rcpp:::CxxFlags()"` $(LIBRARIES) $(LFLAGS) ' \
R CMD SHLIB fastRPCA.cpp -o../bin/RProgram.so -L../bin -llibrary
Then I call it in R:
dyn.load("fastRPCA.so", local=FALSE);
Please note I would prefer not setting MKL as the BLAS/LAPACK alternative for R, so that when other people use this code they don't have to change it for all of R. As such, I am trying to just use it in the C code.
How can I make the program multithread in Rcpp just as it does when run outside of R?
Based on this discussion, I am concerned that this is not possible. However, I wanted to ask, because I believe that since Intel MKL uses the OpenMP, perhaps there was some way to make it work.
There are basically two rules for working with R code:
Create a package.
Follow rule 1.
You are making your life hard by ignoring these.
Moreover, there are a number of packages on CRAN happily using OpenMP -- study those. You need to know and learn about thread setting -- see eg the RhpcBLASctl package which does this.
Lastly, you can of course connect R directly with the MKL; see the gcbd package and its vignette.
Edit three years later: See this post for details on installing the MKL easily on a .deb system
I'm trying to call R from c++ on linux via RInside, I compiled R-2.15.1 from source with gcc version 4.5.3 (Debian 4.5.3-1) , I don't have sudo rights to use apt-get install. I'm using OpenBlas and a system optimized lapack. The blas and lapack libraries work fine for many scalapack applications
I installed R with
./configure --with-blas="-I/lib/OpenBLAS-v0.2.3-0/xianyi-OpenBLAS-48f075c/install/include -L/lib/OpenBLAS-v0.2.3-0/xianyi-OpenBLAS-48f075c/install/lib -lopenblas -lgfortran" --with-lapack="/usr/lib/liblapack.so -lgfortran" --enable-BLAS-shlib=yes --enable-R-shlib --enable-R-static-lib --prefix= .
which installed and runs fine,I ran make check with no errors, also all the packages (Rcpp and RInside) installed fine..
however when i use the given RInside makefile , the basic hello world example from /standard/rinside_sample0.cpp compiles! but it does not run and i get the following error
./rinside_sample0: error while loading shared libraries: libRblas.so: cannot open shared object file: No such file or directory
the file libRblas.so exists and is in the R/lib folder,
when i try to link it manually with the g++ command the make file creates or linking as follows i get a segmentation fault
/R/lib/libRblas.so ./hello_world
Segmentation fault
EDIT: heres how the example make file tries to compile an example, (which compiles fine) but won't run with the above missing libRblas.so error
g++ -I/nfs/user03/jimmie21/libs/lib64/R/include -I/nfs/user03/jimmie21/libs/lib64/R/library/Rcpp/include -I/nfs/user03/jimmie21/libs/lib64/R/library/RInside/include -g -O2 -Wall -I/usr/local/include hello_world.cpp -L/nfs/user03/jimmie21/libs/lib64/R/lib -lR -L/nfs/user03/jimmie21/libs/lib64/R/lib -lRblas -L/nfs/user03/jimmie21/libs/lib64/R/lib -lRlapack -L/nfs/user03/jimmie21/libs/lib64/R/lib -lRblas -L/nfs/user03/jimmie21/libs/lib64/R/library/Rcpp/lib -lRcpp -Wl,-rpath,/nfs/user03/jimmie21/libs/lib64/R/library/Rcpp/lib -L/nfs/user03/jimmie21/libs/lib64/R/library/RInside/lib -lRInside -Wl,-rpath,/nfs/user03/jimmie21/libs/lib64/R/library/RInside/lib -o hello_world
Couple of things:
Reproducible examples, please
You have a non-standard setup
With the script from 1), try it on a standard setting as that is how Rcpp / RInside get developed and tested (on Ubuntu / Debian)
The Rcpp test suite now contains almost 800 unit tests from around 350 unit test functions. These do not seg.fault, so the issue is at your end. Similarly, RInside has dozens of examples in the four examples/ subdirectories. This also works.
It may be as easy as tweaking the Makefile / Makevars files to make sure you get your libraries in all cases. But we can't tell as there is nothing reproducible here.
Edit If you want to link with libRblas.so then you have a completely non-standard setup as the R packages for Debian / Ubuntu as use the external BLAS. Again, not an RInside issue.
I fixed the problem by adding the R install path lib ../R/lib: to the beginning of LD_LIBRARY_PATH after that all the examples compiled and run fine
I'm having trouble building a simple c++ program that tests out regex's from the boost library. The problem that I'm having is occurring in the linking stage and I don't know enough to fix the error on my own.
In the .cpp program that uses regexes I used the following include line.
#include <boost/regex.hpp>
I don't know enough to figure out what command I should use to build the program using g++. I tried using the following command line (and variations of it) to build the program.
g++ -I/usr/include/regex -L/usr/lib -llibboost_regex main.cpp -o regex_test
Other information that might be relevant:
Operating system: Arch linux
g++ version: 4.6.2 20120120 (prerelease)
Any help would be appreciated.
Assume you have installed Boost with the boost and boost-libs packages,
The header <boost/regex.hpp> should exist in /usr/include/boost/regex.hpp. You don't need to use any -I flags since /usr/include should be included by default.
You shouldn't need the -L flag either since /usr/lib should also be included by default when linking.
When using the -l flag to link with a library libfoo.so, the leading "lib" part should be removed.
The command line should therefore be:
g++ main.cpp -o regex_test -lboost_regex