other_languages.txt
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Python with other programming languages (especially C)

Best of both worlds: convenience of Python, performance of compiled code

One of Python's super powers!
 Essential to Python's versatility and popularity
 Enables Python to do production scientific/technical computing
 Leverages decades of C (etc.) development, stand on the shoulders of giants

How: use the usual Python import statement to import *extension modules*:
 Written in other languages
 Compiled (to .so in Unix, .dll in Windows, etc.)

Extensions must be coded, built in a Python-aware way, using special tools
 Can be wrappers for already-written C, Fortran, ....
 Build is usually automated in setup.py, similar to Makefile 

Available languages and tools depend on which Python you are using:
CPython (C, C++), Jython (Java), Iron Python (C#, .NET), PyPy ("other")







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Python with C

C-API - Extension modules - program in C - how Python, NumPy itself are built 
         - for C and Python internals experts

 Extending Python with C or C++
 http://docs.python.org/extending/extending.html


SWIG - used in some big important systems: wxPython, GNU Radio, ...
         - complicated, steep learning curve

 Python C++ and SWIG
 http://wxpython.org/OSCON2008/Python C++ and SWIG.pdf


Cython (forked from Pyrex) - newest and easiest - Seattle connection (SAGE)
         - new language, superset of Python with optional C-like declarations
           entire programming language with its own compiler for Python extensions!
	 - wrap C code or write new code

 Cython: C extensions for Python
 http://cython.org/



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Cython how-to:

 - install cython
 - write foo.pyx, similar to foo.py but with optional declarations
 - write setup.py that runs cython to build extension module foo.o
 - python setup.py build_ext --inplace # compile cython,then compile c and link
 - put foo.o on your PYTHONPATH
 - in Python: import foo

>>> integrate.integrate_f(0,1.5,20000000) # takes > 10 sec
0.77823777512908388

integratex.... takes < 1 sec

Better than 10x speedup