ODE_theano.py

import numpy
import theano
import theano.tensor as T

rng = numpy.random
N = 20
dt= theano.shared(0.1, name="dt")

x = theano.shared(rng.randn(N), name="x")
y = theano.shared(rng.randn(N), name="y")
z = theano.shared(rng.randn(N), name="z")

p=T.scalar("p")
b=T.scalar("b")
r=T.scalar("r")

#lorenz                                                                                                                                                                                 
xn=x+dt*(y-x)*p
yn=y+dt*(-x*z+r*x-y)
zn=z+dt*(x*y-b*z)

lorenz = theano.function(
    inputs=[p,b,r],
    outputs=[xn,yn,zn],
    updates={x:xn,y:yn,z:zn})

for i in xrange(10):
    print lorenz(10,28,8./3)

#rossler                                                                                                                                                                                
a=T.scalar("a")
b=T.scalar("b")
c=T.scalar("c")

rossler_param=[a,b,c]
rossler_out=[
    x+dt*(-y-z),
    x+dt*(x+a*y),
    z+dt*z*(x-c)
    ]

rossler = theano.function(
    inputs=rossler_param,
    outputs=[xn,yn,zn],
    updates=tuple(zip(*[[x,y,z],rossler_out])))
    
for i in xrange(10):
 print rossler(0.2,0.2,5.7)