import numpy as np
import matplotlib.pyplot as plt

plt.style.use('ggplot')
#plt.figure(figsize=(20,10))

N=50000 # number of steps
T=20   # simulation time in seconds

c = 1
l = 1
r = 4

t = np.empty(N)
Vi = np.empty(N)
I = np.empty(N)
V = np.empty(N)

dt=T/N;

# initial values
V[0]=0
I[0]=0

for k in range(0,N-1):
	
	#Vi[k]=1; # Step input
	#Vi[k]=t[k]; # Ramp input
	Vi[k]=np.sin(0.98*t[k])

	I[k+1]=I[k]-(1/l)*V[k]*dt-r/l*I[k]*dt+Vi[k]/l*dt	
	V[k+1]=V[k]+I[k+1]/c*dt
	t[k+1]=t[k]+dt	

plt.plot(t,Vi,label='Input Signal')
plt.plot(t,V,label='Capacitor Voltage')
plt.plot(t,I,label='Inductor Current')


plt.xlabel('Time (s)')
plt.title('Driven RLC circuit')
plt.legend()
plt.show()