GNU GSL BLAS library, undefined symbols - c

Question

Is there anyone that can give me a simple run down of how to install the GSL library so that it'll work with XCode (5.1) on a Mac (Mavericks, 10.9)? I keep getting this error:
Undefined symbols for architecture x86_64:
"_gsl_matrix_add", referenced from:
_myProject in main.o
I initially installed GSL 1.16 in /Library/gsl-1.16
I did the whole ./configure, make, and make install
THINGS I HAVE TRIED TO FIX THIS:
1) Going to "Build Settings" in XCode and adding "/Library/gsl-1.16"
to both the library and header search paths
2) Creating a symbolic link from the ...usr/include path (... being the SDK (MacOSX 10.9) location XCode is using) to the Library path.
3) Adding "-lgsl" to the "Arguments passed on Launch" section of my project's scheme
4) Adding "-Wall -I/Library/include" to the "Arguments passed on Launch" section of my project's scheme
Nothing has worked. Xcode reports that it can find the headers, but it can't reference the methods associated with the header files. Truly interesting. I have no idea, I've done everything I can think of and Google.

Answer 1

From your description it is difficult to locate whether you set the build settings correctly. I installed GSL using macports and not sure how it would be like if installed directly from source. But I believe you need to figure out where the make install installs the GSL library and header to, since typically they are installed into different paths, which are not the path you run make install.
And since typically make install will install headers to /usr/local/include and libraries to /usr/local/lib, I guess it is possible that you set the wrong path to the libraries. Assume you figured out that your GSL library is in /usr/local/lib (and typically they should), you just need to do one of the two things (not both):
Change Library search path to /usr/local/lib. (and header search path to /usr/local/include as you did)
Change compiler arguments to -Wall -I/usr/local/include -L/usr/local/lib. (last two arguments start with capital i and capital L).
Here is the procedure how I install GSL using macports and set up it in Xcode to run a matrix addition:
Install macports if you haven't done it. Refer to https://www.macports.org/install.php .
In terminal, type sudo port install gsl and have several cups of coffee.
By default, macports installs librarys to /opt/local/lib and headers to /opt/local/include. So after you create a C++ project in Xcode, go to build settings, add the three settings below:
Library search paths: /opt/local/lib
Header search paths: /opt/local/include
Other linker flags: -lgsl (depending on what you want to do, you may also need to add -lgsl -lgslcblas and other flags.)
Now it is up and running. Include <gsl/gsl_matrix.h> and gsl_matrix is ready to use.