#### 2.2.1 Linking programs with the library

The library is installed as a single file, `libgsl.a`. A shared version of the library `libgsl.so` is also installed on systems that support shared libraries. The default location of these files is `/usr/local/lib`. If this directory is not on the standard search path of your linker you will also need to provide its location as a command line flag.

To link against the library you need to specify both the main library and a supporting CBLAS library, which provides standard basic linear algebra subroutines. A suitable CBLAS implementation is provided in the library `libgslcblas.a` if your system does not provide one. The following example shows how to link an application with the library,

    $ gcc -L/usr/local/lib example.o -lgsl -lgslcblas -lm

The default library path for `gcc` searches `/usr/local/lib` automatically so the `-L` option can be omitted when GSL is installed in its default location.

The option `-lm` links with the system math library. On some systems it is not needed.3

For a tutorial introduction to the GNU C Compiler and related programs, see An Introduction to GCC (ISBN 0954161793).4

#### Footnotes

### (3)

It is not needed on MacOS X.

### (4)

http://www.network-theory.co.uk/gcc/intro/