In [1]:

    

import numpy as np
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
from matplotlib import cm
from matplotlib.ticker import LinearLocator, FormatStrFormatter
import matplotlib.animation as manimation


    

In [2]:

    

r = 1
r2 = r ** 2
c = 1.0

t0 = 0
tf = 0.5
dt = 0.01
t = np.arange(t0, tf+dt, dt)
len_t = len(t)

x0 = 0
xf = 1
dx = c * dt / r
x = np.arange(x0, xf+dx, dx)
len_x = len(x)

y0 = 0
yf = 1
dy = dx
y = np.arange(y0, yf+dy, dy)
len_y = len(y)

z = np.zeros((len(x), len(y), len(t)))
zc = np.zeros((len(x), len(y)))

zc[0, :] = np.ones(len(zc[0, :]))
zc[len(x)-1, :] = np.ones(len(zc[len(x)-1, :]))
zc[:, 0] = np.ones(len(zc[:, 0]))
zc[:, len(y)-1] = np.ones(len(zc[:, len(y)-1]))


    

In [3]:

    

k1 = 1000
k2 = 500
xc1 = 0.3
xc2 = 0.6


    

In [4]:

    

for i in range(1, len_x-1):
    for j in range(1, len_y-1):
        if(zc[i,j] != 1):
            x_i = i * dx
            y_i = j * dy
            z[i, j, 0] = np.exp(-k1 * (x_i - xc1) ** 2) + np.exp(-k1 * (y_i - xc2) ** 2)


    

In [5]:

    

for k in range(0, len_t-1):
    for i in range(0, len_x):
        for j in range(0, len_y):
            if zc[i,j] == 1:
                continue
            if k > 0:
                zp = z[i,j,k-1]
            else:
                zp = 0
            (t_i, x_i, y_i) = (k*dt, i*dx, j*dy)
            z[i, j, k+1] = r2 * (z[i+1,j,k] + z[i-1,j, k] + z[i,j+1,k] + z[i, j-1, k]) - zp + 2*(1-2*r2)*z[i, j, k]
    if k % 25 == 0:
        print(len_t - k)


    

    




51
26

In [6]:

    

plt.matshow(z[:,:,])

plt.colorbar()
plt.show()


    

    




---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-6-f79e1f95174a> in <module>()
----> 1 plt.matshow(z[:,:,])
      2 plt.clim(-5, 5)
      3 plt.colorbar()
      4 plt.show()

/usr/lib/python3/dist-packages/matplotlib/pyplot.py in matshow(A, fignum, **kw)
   2256         ax  = fig.add_axes([0.15, 0.09, 0.775, 0.775])
   2257 
-> 2258     im = ax.matshow(A, **kw)
   2259     sci(im)
   2260 

/usr/lib/python3/dist-packages/matplotlib/axes/_axes.py in matshow(self, Z, **kwargs)
   6837         """
   6838         Z = np.asanyarray(Z)
-> 6839         nr, nc = Z.shape
   6840         kw = {'origin': 'upper',
   6841               'interpolation': 'nearest',

ValueError: too many values to unpack (expected 2)

In [14]:

    

FFMpegWriter = manimation.writers['ffmpeg']
metadata = dict(title='Movie Test', artist='Matplotlib',
        comment='Movie support!')
writer = FFMpegWriter(fps=4, metadata=metadata)

fig = plt.figure()
ax = fig.add_subplot(111)


with writer.saving(fig, "writer_test.mp4", 60):
    for i in range(len_t):
        ax.matshow(z[:,:,i])
        plt.clim(-5, 5)
        writer.grab_frame()


    

    




---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-14-8771e1de10a0> in <module>()
     11     for i in range(len_t):
     12         ax.matshow(z[:,:,i])
---> 13         plt.clim(-5, 5)
     14         writer.grab_frame()

/usr/lib/python3/dist-packages/matplotlib/pyplot.py in clim(vmin, vmax)
   2183     im = gci()
   2184     if im is None:
-> 2185         raise RuntimeError('You must first define an image, eg with imshow')
   2186 
   2187     im.set_clim(vmin, vmax)

RuntimeError: You must first define an image, eg with imshow

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