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#!/usr/bin/env python3
######################################################################
# Software License Agreement (BSD License)
#
# Copyright (c) 2015, Caleb Voss and Wilson Beebe
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
# * Neither the name of the Rice University nor the names of its
# contributors may be used to endorse or promote products derived
# from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
######################################################################
# Authors: Caleb Voss, Wilson Beebe
import matplotlib.pyplot as plt
from pylab import meshgrid, arange, quiver, quiverkey, sqrt
import numpy as np
def makeVectorField(f, xmin, xmax, ymin, ymax, step):
X, Y = meshgrid(arange(xmin, xmax, step), arange(ymin, ymax, step))
U, V = zip(*map(lambda xx: f(*xx), zip(X, Y)))
Q = quiver(X, Y, U, V, units='width')
quiverkey(Q, 0, 0, 4, '', coordinates='figure', labelpos='W')
fig = plt.figure()
ax = fig.gca(aspect='equal')
x = np.loadtxt("vfrrt-nonconservative.path")
makeVectorField(lambda x, y: (y / sqrt(x * x + y * y + 1e-6), -x / sqrt(x * x + y * y + 1e-6)),
-6, 6, -6, 6, 0.5)
ax.plot(x[:, 0], x[:, 1])
plt.show()
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