Commit by inagaki

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+env/
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*,cover
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Emacs backups
+*~
+
+# Pycharm IDE directory
+.idea
+
+# IPython Notebooks
+*/.ipynb_checkpoints
+
+# Ipython just for testing
+archive_notebooks
+
+# svg files
+*.svg
+
+# memo for codeship setting
+codeship_settings.txt

inagaki/predator_prey.py

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+#!/usr/bin/env python
+
+import numpy as np
+import scipy.integrate as desol
+import matplotlib.pyplot as plt
+
+def predator_prey(f, t, a, b, c, d):
+    #
+    #  dx/dt = ax - bxy
+    #  dy/dt = cxy - dy
+    #
+    #  f[0]    - x: Population of prey
+    #  f[1]    - y: Population of predetor
+    #  t       - Time
+    #  a,b,c,d - Control parameters
+    #
+    return [a*f[0]-b*f[0]*f[1], c*f[0]*f[1]-d*f[1]]
+
+
+#model
+#eq1 = r"$\frac{dx}{dt} = ax - bxy$"
+#eq2 = r"$\frac{dy}{dt} = cxy - dy$"
+eq1 = r"$dx/dt = ax - bxy$"
+eq2 = r"$dy/dt = cxy - dy$"
+
+#input parameters
+a = 1.0
+b = 1.0
+c = 1.0
+d = 1.0
+header = r"$a={0:.1f}, b={1:.1f}, c={2:.1f}, d={3:.1f}$".format(a, b, c, d)
+
+#initial condition
+f0 = [1.0, 0.1]
+
+#independent variable
+nt   = 1000
+tmax = 30.0
+dt = tmax/nt
+t  = dt*np.arange(nt)
+
+f = desol.odeint(predator_prey, f0, t, args=(a,b,c,d))
+
+#plot
+prey = f[:,0]
+predator = f[:,1]
+
+fig = plt.figure()
+ax = fig.add_axes([0.15, 0.1, 0.8, 0.8])
+ax.plot(t, prey, color='r', label=r"$x$: prey")
+ax.plot(t, predator, color='b', label=r"$y$: predator")
+handles, labels = ax.get_legend_handles_labels()
+ax.legend(handles, labels, loc='best')
+ax.text(21, 2.7, eq1, fontsize=16)
+ax.text(21, 2.5, eq2, fontsize=16)
+ax.set_xlabel("Time")
+ax.set_ylabel("Population")
+ax.set_title(header)
+plt.show()