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Compute and visualize pseudospectra of matrices (like eigtool)

Project description

# PseudoPy [![Build Status](https://travis-ci.org/andrenarchy/pseudopy.png?branch=master)](https://travis-ci.org/andrenarchy/pseudopy)

PseudoPy computes and visualizes the pseudospectrum of a matrix. It is a Python version of the original [eigtool](http://www.cs.ox.ac.uk/pseudospectra/eigtool/) by Thomas G. Wright. The algorithms used in this package can be found in the book [Spectra and pseudospectra](http://press.princeton.edu/titles/8113.html) by [Nick Trefethen](http://www.maths.ox.ac.uk/people/profiles/nick.trefethen) and [Mark Embree](http://www.caam.rice.edu/~embree/).

## Example
The pseudospectrum of the Grcar matrix looks like this:

![Pseudospectrum of Grcar matrix](grcar.png)

The above figure can be created with the following lines of code:
```python
from pseudopy import NonnormalMeshgrid, demo
from matplotlib import pyplot
from scipy.linalg import eigvals

# get Grcar matrix
A = demo.grcar(32).todense()

# compute pseudospectrum
pseudo = NonnormalMeshgrid(A,
real_min=-1, real_max=3, real_n=400,
imag_min=-3.5, imag_max=3.5, imag_n=400)
# plot
pseudo.plot([10**k for k in range(-4, 0)], spectrum=eigvals(A))
pyplot.show()
```

## Installation
```pip install pseudopy```

Note that you may need to add `sudo` if you want to install it system-wide.

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