ctypesGsl 0.4

UNKNOWN

ctypesGsl is a Python binding for the GSL library using the ctypes package. It is probably somewhat slower than pygsl but has other advantages:

1. It is very easy to install, the only dependency (except for GSL itself) is the ctypes package, standard since Python 2.5. No compilation or is required during installation. The implementation is simpler too as it does not require SWIG wrappers, C code or shared libraries.

2. ctypes seems to be the preferred future way to do Python bindings, since it is independent from python implementation used, e.g. it should work with PyPy.

Currently it is slowly becoming reasonably complete. Implemented are:

error handling basic function complex numbers polynomials special functions vectors matrices permutations (incomplete) combinations BLAS linear algebra eigensystems numerical integration random number generators quasi random number generators probability distributions Monte Carlo integration ordinary differential equations numerical integration Chebyshev approximations one dimensional root finding one dimensional minimization multidimensional root finding multidimensional minimization

License

GPL v.3, see LICENSE.txt

Installation

There is a (somewhat experimental) setup.py script in the top-level directory.

Alternatively, just copy the ctypesGsl directory to

/usr/local/lib/python2.5/site-packages/

or wherever you keep your local python packages. You’re ready to go:

>>> import ctypesGsl
>>> ctypesGsl.expm1(1)
1.7182818284590451

the test_cgsl.py file contains some examples based on GSL tests.

Design

The idea is that the package should be usable like a standard python library. The low level functions are thus often wrapped in python functions which try to hide some of the complexity.

The higher level interface does error handling (exceptions are raised if return value is not GSL_SUCCESS), and tries to make common usage easy, e.g. gsl_complex numbers can be used just as standard Python complex numbers, tries to allocate integration workspace of reasonable size if none is provided, etc.

See the test_cgsl.py file for examples.

Error handling

There are two ways to check for errors in GSL: internal error handler, and return values. ctypesGsl handles both. The return values are automatically checked and (by default) an exception is raised if the return value indicates an error.

Unfortunately ctypes does not propagate exceptions raised inside callback functions to the main thread, so if an exception is raised in the internal error handler, a backtrace is printed but the program continues. Internal GSL error handler is thus (by default) redefined to only print a warning message.

Both internal and return value error handlers can be redefined.

Documentation

None at the moment. See test_cgsl.py file for usage examples.