In this section we describe most of the functions defined in the core CCL libraries. These include standard I/O functions, mathematical funtions, list operations and graphics operations. The list of functions here may not be complete. Look at the actual library files (in $CCL_ROOT/lib/) for a complete list of functions available and brief descriptions of their use. To use the functions in a library, simply include it at the beginning of your code. CCL automatically looks in $CCL_ROOT/lib/ and then in the local directory for included files.