"AttributeError: 'list' object has no attribute 'ravel'"

Question

I have a system of differential equations and need to calculate the Jacobian. The code below throws AttributeError: 'list' object has no attribute 'ravel'. What am I missing?

import numpy as np
import numdifftools as ndt

def rhs(z, t=0):
    x,y = z

    xdot = (x/5 + y)*(-x**2+1)
    ydot = -x*(-y**2+1)

    return [xdot, ydot]

Jfun = ndt.Jacobian(rhs)

Jfun([1,1])

Solution

Just do:

return np.array([xdot, ydot])

instead. This should work...

Comments

[emma]

strange..i was pretty sure i've tried that before..anyway, it worked! thank you very much - i wish every problem could be solved in one line!

[Saullo G. P. Castro]

@klim I found out this was the problem based on your error message... since ravel is a method of the ndarray object, it was likely that returning the array instead of the list would solve the problem