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Python binding for cvodes from the sundials library.

Project description

Build status PyPI version License coverage

pycvodes provides a Python binding to the Ordinary Differential Equation integration routines from cvodes in the SUNDIALS suite. pyvodes allows a user to numerically integrate (systems of) differential equations. Note that routines for sensitivity analysis is not yet exposed in this binding (which makes the functionality essentially the same as cvode).

The following multistep methods are available:

  • bdf
  • adams

Note that bdf (as an implicit stepper) require a user supplied callback for calculating the jacobian.

Documentation

Autogenerated API documentation is found here: https://bjodah.github.com/pycvodes

Installation

Simplest way to install is to use the conda package manager:

$ conda install -c bjodah pycvodes pytest
$ python -m pytest --pyargs pycvodes

tests should pass.

Binary distribution is available here: https://anaconda.org/bjodah/pycvodes

Source distribution is available here: https://pypi.python.org/pypi/pycvodes

Example

The classic van der Pol oscillator (see examples/van_der_pol.py)

>>> import numpy as np
>>> from pycvodes import integrate_predefined  # also: integrate_adaptive
>>> mu = 1.0
>>> def f(t, y, dydt):
...     dydt[0] = y[1]
...     dydt[1] = -y[0] + mu*y[1]*(1 - y[0]**2)
...
>>> def j(t, y, Jmat, dfdt=None, fy=None):
...     Jmat[0, 0] = 0
...     Jmat[0, 1] = 1
...     Jmat[1, 0] = -1 - mu*2*y[1]*y[0]
...     Jmat[1, 1] = mu*(1 - y[0]**2)
...     if dfdt is not None:
...         dfdt[:] = 0
...
>>> y0 = [1, 0]; dt0=1e-8; t0=0.0; atol=1e-8; rtol=1e-8
>>> tout = np.linspace(0, 10.0, 200)
>>> yout, info = integrate_predefined(f, j, y0, tout, atol, rtol, dt0,
...                                   method='bdf')
>>> import matplotlib.pyplot as plt
>>> series = plt.plot(tout, yout)
>>> plt.show()  # doctest: +SKIP
https://raw.githubusercontent.com/bjodah/pycvodes/master/examples/van_der_pol.png

License

The source code is Open Source and is released under the simplified 2-clause BSD license. See LICENSE for further details.

Contributors are welcome to suggest improvements at https://github.com/bjodah/pycvodes

Author

Björn I. Dahlgren, contact:

  • gmail address: bjodah
  • kth.se address: bda

Project details


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