update juliac readme instrucitons

Author: baggepinnen

README.md

@@ -198,9 +198,31 @@ The fixed-point controller behaves roughly the same in this case, but artifacts
 ## Compilation using JuliaC
 The file `examples/juliac/juliac_pid.jl` contains a JuliaC-compatible interface that can be compiled into a C-callable shared library using JuliaC. To compile the file, run the following from the `examples/juliac` folder:
 ```bash
-julia +nightly --project <PATH_TO_JULIA_REPO>/julia/contrib/juliac.jl --output-lib juliac_pid --trim=unsafe-warn --compile-ccallable juliac_pid.jl
+julia +nightly --project <PATH_TO_JULIA_REPO>/julia/contrib/juliac.jl --output-lib juliac_pid --experimental --trim=unsafe-warn --compile-ccallable juliac_pid.jl
 ```
-where `<PATH_TO_JULIA_REPO>` should be replaced with the path to the Julia repository on your system. The command will generate a shared library `juliac_pid` that can be called from C. The file `examples/juliac/juliac_pid.h` contains the C-compatible interface to the shared library.
+where `<PATH_TO_JULIA_REPO>` should be replaced with the path to the Julia repository on your system. The command will generate a shared library `juliac_pid` that can be called from C. The file `examples/juliac/juliac_pid.h` contains the C-compatible interface to the shared library. The C program may be compiled with a command like
+```bash
+export LD_LIBRARY_PATH=<PATH_TO_JULIA_REPO>/julia/usr/lib:$LD_LIBRARY_PATH
+gcc -o pid_program test_juliac_pid.c -I <PATH_TO_JULIA_REPO>/julia/usr/include/julia -L<PATH_TO_JULIA_REPO>/julia/usr/lib -ljulia -ldl
+```
+and then run by
+```bash
+./pid_program
+```
+which should produce the output
+```
+DiscretePIDs/examples/juliac> ./pid_program 
+Loading juliac_pid.so
+Loaded juliac_pid.so
+Finding symbols
+Found all symbols!
+calculate_control! returned: 1.000000
+calculate_control! returned: 2.000000
+calculate_control! returned: 3.000000
+calculate_control! returned: 3.000000
+calculate_control! returned: 3.000000
+```
+At the time of writing, this requires a nightly version of julia
 
 
 ## See also