Ground motion models implemented in Python.

## Project description

======
pyrotd
======

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Acceleration response spectrum calculations implemented in Python.

Introduction
------------

Computes the normal and rotated pseudo-acceleration response spectrum of an
earthquake ground motion. The calculation of the response spectrum is performed
using frequency domain transfer functions, as well as frequency domain
interpolation methods to insure that the time step of the motions is greater
than 10 times the natural frequency of the oscillator frequency. Two
perpendicular ground motions can be rotated to compute the response at various
percentiles. For example, the minimum, median, and maximum could be computed
using percentiles of 0, 50, and 100. The orientation of both the minimum and
maximum percentile are provided, but not orientation is provided for other
percentiles because the rotate spectral acceleration is not monotonically
increasing.

Installation
------------

``pyrotd`` is available from the Python Cheese Shop::

pip install pyrotd

Example
-------

Spectral accelerations may be computed for a single time series::

osc_damping = 0.05
osc_freqs = np.logspace(-1, 2, 91)
spec_accels = pyrotd.calc_spec_accels(time_step, accels, osc_freqs, osc_damping)

Rotated spectral accelerations may be computed for a pair of time series::

rot_osc_resps = pyrotd.calc_rotated_spec_accels(time_step, accels_a, accels_b,
osc_freqs, osc_damping)
A more detailed example is in `this`_ Jupyter Notebook.

:: _`this`: https://github.com/arkottke/pyrotd/blob/master/example.ipynb

History
-------

.. include:: HISTORY.rst

Contributing
-------------

.. include:: CONTRIBUTING.rst

History
=======

0.2.0 (2017-02-20)
------------------
- Changed from camelCase to underscores
- Added PEER NGA West2 test cases
- Fixed: numpy.array creation

0.1.0 (2016-03-04)
------------------
- First release on PyPI.