# How can i resolve this?

Hello, I’m trying of solve this differential equations and graphing them , but i have this errors, and i dont know what I´m doing wrong, could you help me? it´s a predator-prey dinamics

``````import numpy as np
import matplotlib.pyplot as plt
from numpy import *
from numpy.random import *
from matplotlib.pyplot import *
from scipy.integrate import odeint

#tasa de crecimiento de las presas
r = 10
#interacciones
a = 1
#tasa de crecimiento de los lobos
c = 2
m = 2

def depre(t,IR):
M = IR[1]
W = IR[2]
dM= r*M-a*W
dW = a*M*c-m*W
dIR = [dM,dW]
return  dIR

IR0 = [1000,0,11]
t = np.linspace(0,15,1000)
IR = odeint(depre, IR0, t)

M = IR[: , 0]
W = IR[: ,1]

plt.show()
``````

the errors are:

``````RuntimeError                              Traceback (most recent call last)
<ipython-input-2-aa21044ab78e> in <module>
17 x0 = [1000, 0, 100]
18 t = np.linspace(0,15,1000)
---> 19 x = odeint(dep,x0,t)
20
21 M = x[:,0]

~\anaconda3\lib\site-packages\scipy\integrate\odepack.py in odeint(func, y0, t, args, Dfun, col_deriv, full_output, ml, mu, rtol, atol, tcrit, h0, hmax, hmin, ixpr, mxstep, mxhnil, mxordn, mxords, printmessg, tfirst)
239     t = copy(t)
240     y0 = copy(y0)
--> 241     output = _odepack.odeint(func, y0, t, args, Dfun, col_deriv, ml, mu,
242                              full_output, rtol, atol, tcrit, h0, hmax, hmin,
243                              ixpr, mxstep, mxhnil, mxordn, mxords,

RuntimeError: The size of the array returned by func (2) does not match the size of y0 (3).

``````

You are returning an array of size 2 while passing an initial value array of size 3. This issue can be easily resolved if you take `x0 = [0,11]` instead of `x0 = [1000,0,11]`; since you are not even using the first element `x0[0]` anywhere in your function `depre`.