undefined reference

[Cheng Xing]

Well, I input gsl-config --lib, and get
-L/usr/local/lib -lgsl -lgslcblas -lm
So is that ok to compile with 'gcc filename -lgsl -lgslcblas -lm'?
I did compile successfully this time, but got another warning message 
when run the file a.out. It said:
a.out: error while loading shared libraries: libgsl.so.0 : cannot open 
shared object file: No such file or directory.
But I did find this file in my usr/local/lib

-Cheng