I have a made a solver which can interchange between scipy.integrate.ode
and scipy.integrate.odeint
. Here is the code.
def f(y,s,C,u,v):
y0 = y[0] # u
y1 = y[1] # u'
y2 = y[2] # v
y3 = y[3] # v'
dy = np.zeros_like(y)
dy[0] = y1
dy[2] = y3
C = C.subs({u:y0,v:y2})
dy[1] = -C[0,0][0]*dy[0]**2
-2*C[0,0][1]*dy[0]*dy[2]
-C[0,1][1]*dy[2]**2
dy[3] = -C[1,0][0]*dy[0]**2
-2*C[1,0][1]*dy[0]*dy[2]
-C[1,1][1]*dy[2]**2
return dy
def solve(C,u0,s0,s1,ds,solver=None):
from sympy.abc import u,v
if solver == None: # use lsoda from scipy.integrate.odeint
s = np.arange(s0,s1+ds,ds)
print 'Running solver ...'
return sc.odeint(f,u0,s,args=(C,u,v))
else: # use any other solver from scipy.integrate.ode
r = sc.ode(f).set_integrator(solver) # vode,zvode,lsoda,dopri5,dop853
r.set_f_params(C,u,v)
r.set_initial_value(u0)
#t = []
y = []
print 'Running solver ...'
while r.successful() and r.t <= s1:
r.integrate(r.t + ds)
y.append(r.y)#; t.append(r.t)
return np.array(y)
The problem I experience is as following. If I decide to use the solver from scipy.integrate.odeint
then the parameters of f
have to be specified in the order as they are in the code. However, if I decide to use the solvers from scipy.integrate.ode
I have to change the order of the parameters of the function f(y,s,C,u,v)
to f(s,y,C,u,v)
, otherwise I get the error
TypeError: 'float' object has no attribute '__getitem__'
If I do this, then scipy.integrate.odeint
generates the same error for f
defined as f(s,y,C,u,v)
. How can I operate with a unified f
regardless of the order of the parameters ?
Edit :
To sum the problem up :
scipy.integrate.ode
solvers work if the function f is defined as f(s,y,C,u,v)
, and scipy.integrate.odeint
solver works if the function f is defined as f(y,s,C,u,v)
. Why is this occurring, and how I can I fix this?
Edit :
Scipy -- version 0.16.0
See Question&Answers more detail:
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