[Tutor] Solve wave equation

[David Craig]

OK so I can solve the equation but now I am having trouble plotting the 
solution! I would like to produce a surface plot with colors defined by 
p and animate it. That is plot the value of p at all x and z, over time 
(t).  My code to get p is below but I really have no idea how to plot 
this. Anyone know the best way to go about this?
thanks,
D

-------- Original Message --------
Subject: 	Re: [Tutor] Solve wave equation
Date: 	Thu, 23 Feb 2012 15:24:45 +0000
From: 	David Craig <dcdavemail at gmail.com>
To: 	tutor at python.org



Hooray it works,
thanks

On 02/23/2012 01:39 PM, Ken Oliver wrote:
>  Do you really want dt = 1**-4 or would 10**-4 be better
>
>  -----Original Message-----
>>  From: David Craig<dcdavemail at gmail.com>
>>  Sent: Feb 23, 2012 7:57 AM
>>  To: tutor at python.org
>>  Subject: [Tutor] Solve wave equation
>>
>>  Hi,
>>  I am trying to write some code that will solve the 2D wave equation by
>>  the finite difference method, but it just returns an array full of zeros
>>  and NaN's. Not sure where I am going wrong, the code is attached so if
>>  could someone point me in the right direction I'd appreciate this.
>>  Thanks
>>  D
>
>    .
>

# 2D Finite Distance Wave Equation.
from pylab import *
from numpy import math

ion()

# Set up variables.
nx = 100
nz = 100
nsteps = 300
c = 3500
dt = 10**-4
h = 1
t = arange(0,nsteps,dt)



# Define source as a spike.
s = zeros(nsteps)
s[1] = 1
s[2] = 2
s[3] = 1

# Position source.
xs = 50
zs = 50
##plot(t,s)
##show()

# Set up pressure field.
p=empty([nx,nz,nsteps])

for t in range(0,nsteps-1):

     for z in range(0,nz-1):

         for x in range(0,nx-1):

             p[x,z,t] = 0


# Solve wave equation

for t in range(2,nsteps-1):

     for z in range(1,nz-1):

         for x in range(2,nx-1):

             p[xs,zs,t] = s[t]
             k = (c*dt/h)**2

             p[x,z,t] = 2*p[x,z,t-1] - p[x,z,t-2] + k*(p[x+1,z,t-1]-4*p[x,z,t-1]+p[x-1,z,t-1]+p[x,z+1,t-1]+p[x,z-1,t-1])


         #Plot somehow

         draw()

#close()






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