f() missing 1 required positional argument: 't' - python-3.x

Question

I just tried to execute this code. but it shows always this error:'f() missing 1 required positional argument:'t'
please can you tell me what should I change?
import numpy as np
def f(y,z,t):
return np.array([2*y+z-t,z+y])
import matplotlib.pyplot as plt
from scipy.integrate import odeint
t=np.linspace(0,2,1000)
sol=odeint(f,[0,1],t)
y,z=sol[:,0],sol[:,1]
plt.plot(t,y,label='y')
plt.plot(t,z,label='z')
plt.show()

Answer 1

Depending on what you are trying to do, you can get around it two ways. To pass in additional arguments other than y and t you need to include them as a constant in the function parameter.
import numpy as np
def f(t,y,z):
return np.array([2*y+z-t,z+y])
import matplotlib.pyplot as plt
from scipy.integrate import odeint
t=np.linspace(0,2,1000)
z = 10.0
sol=odeint(f,[0,1],t, tfirst=True, args=(z, ))
y,z=sol[:,0],sol[:,1]
plt.plot(t,y,label='y')
plt.plot(t,z,label='z')
plt.show()
This will still cause an error. However, if you are also trying to obtain z as result then you should be able to run:
import numpy as np
def f(t,inp):
y, z = inp
return np.array([2*y+z-t,z+y])
import matplotlib.pyplot as plt
from scipy.integrate import odeint
t=np.linspace(0,2,1000)
sol=odeint(f,[0,1],t, tfirst=True)
y,z=sol[:,0],sol[:,1]
plt.plot(t,y,label='y')
plt.plot(t,z,label='z')
plt.show()
This should run without any errors but you may need to double check that this is the result you are expecting.
(The tfirst argument is just for clarity to make ensure the order of arguments provided is correct, you can remove and re-order if you want as well.)
Documentation for odeint function here: https://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.odeint.html