# FRETBursts Cython extensions¶

Cython is a tool that, among other things, allows to translate annotated python code into C code. The C code can be then compiled into a dynamic library and transparently called from python like any other python library, but with the advantage of a much higher execution speed.

For some core burst-search functions FRETBursts includes both a pure pyhton and a cython version. At import time, the code looks for the compiled version and, if not found, falls back to the pure python version. Therefore, although the compiled cython version is completely optional, it allows to gain significant execution speed in core functions that are potentially executed many times.

Usually the cython extensions are compiled during installation. To manually build the extensions type:

python setup.py build


from the FRETBursts source folder.