Untitled

import matplotlib.pyplot as plt
from math import *

R1=0.53*pow(10,-4)
R2=0.55*pow(10,-4)
C1=2.5*pow(10,-2)
C2=2*pow(10,-2)
qi1=0.5*pow(10,-4)
qi2=1*pow(10,-4)
tf=10
h=0.001

A,B,C=[],[],[]  

def d(x1,x2,t):  
    return (-1/(R1*C1)*x1+(1/(R1*C1))*x2+(qi1/C1))
def f(x1,x2,t):  
    return (1/(R1*C2)*x1)-(1/(R1*C2)+(1/(R2*C2)))*x2+(qi2/C2)
def rungekutta(d,f,x1_0,x2_0,t0): 

    while t0<tf: 
        t=t0+h 
        k1=d(x1_0,x2_0,t0)
        k2=d(x1_0+(h/2)*k1,x2_0+(h/2)*k1,t0+h/2)
        k3=d(x1_0+(h/2)*k2,x2_0+(h/2)*k2,t0+h/2)
        k4=d(x1_0+h*k3,x2_0+h*k3,t0+h)
        l1=d(x1_0,x2_0,t0)
        l2=d(x1_0+(h/2)*l1,x2_0+(h/2)*l1,t0+h/2)
        l3=d(x1_0+(h/2)*l2,x2_0+(h/2)*l2,t0+h/2)
        l4=d(x1_0+h*l3,x2_0+h*l3,t0+h)
        x1=x1_0*(h/6)*(k1+2*k2+2*k3+k4)
        x2=x2_0*(h/6)*(l1+2*l2+2*l3+l4)
        x1_0=x1
        x2_0=x2
        t0=t
        A.append(t)   
        B.append(x1) 
        C.append(x2)
    return x1,x2,t
a=rungekutta(d,f,0,0,0) 
print(a)