[SciPy-User] Problems with dopri45

L. Barrott lb489@cam.ac...
Tue Apr 3 11:29:16 CDT 2012


>On Tue, Apr 3, 2012 at 5:54 AM, L. Barrott <lb489@cam.ac.uk> wrote:
>
>> Hello,
>>
>> I have been trying to get scipy to solve a set of coupled odes and in
>> particular I want to use the dopri 45 method as I want to compare the
>> results to the ode45 method in MATLAB. The code runs along the lines of:
>>
>> def func (t, Y, params):
>>    ...
>>    return (Ydot)
>>
>> with Y a vector. The other ode methods (except dop853 of course) solve 
>> this fine but even if I use the example code on the documentation page 
>> the dopri method returns the following error
>>
>> create_cb_arglist: Failed to build argument list (siz) with enough 
>> arguments (tot-opt) required by user-supplied function 
>> (siz,tot,opt=2,3,0). ...(traceback stuff) _dop.error: failed in 
>> processing argument list for call-back fcn.
>>
>> Any ideas where I am going wrong?
>>
>> Many thanks
>> LB
>>
>
>
>It would help to see more of your code.  Could you include a complete,
>self-contained script that demonstrates the error?
>
>Warren

Even something as simple as;

from scipy.integrate import ode
y0, t0 = [0, 1], 0
def func (t, y, x):
    return [x, y[0]]
r = ode(func).set_integrator ('dopri5')
r.set_initial_value(y0, t0).set_f_params(1)
t1 = 10
dt = 0.1
while r.successful() and r.t < t1:
    r.integrate(r.t+dt)

Will fail and this is lifted straight from the documentation as far as I 
can see. The full error message is

create_cb_arglist: Failed to build argument list (siz) with enough 
arguments (tot-opt) required by user-supplied function (siz,tot,opt=2,3,0). 
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/usr/lib/python2.7/dist-packages/scipy/integrate/ode.py", line 326, 
in integrate
    self.f_params,self.jac_params)
  File "/usr/lib/python2.7/dist-packages/scipy/integrate/ode.py", line 745, 
in run
    x,y,iwork,idid = self.runner(*((f,t0,y0,t1) + tuple(self.call_args)))
_dop.error: failed in processing argument list for call-back fcn.

LB


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