Trapezoidal Method Python Program

#Trapezoidal Method 
#Define Function To Integrate
def f(x):
    return 1/(1+x**2)

#Implementing Trapezoidal Method
def trapezoidal(x0,xn,n):
    #calculate step size
    h=(xn-x0)/n
    
#Finding sum
    integration=f(x0)+f(xn)

    for i in range(1,n):
        k=x0+i*h
        integration=integration+2*f(k)
    integration=integration*h/2

    return integration

#Input section
lower_limit=float(input("Enter lower limit of integration: "))
upper_limit=float(input("Enter upper limit of integration: "))
sub_interval=int(input("Enter number of sub interval: "))

#call trapezoidal function 
result=trapezoidal(lower_limit, upper_limit, sub_interval)
print("Integration result by trapezoidal method is: %0.6f"%(result))