Program for Simpson's 1/3 Rule

In numerical analysis, Simpson's 1/3 rule is a method for numerical approximation of definite integrals. Specifically, it is the following approximation: 

In Simpson's 1/3 Rule, we use parabolas to approximate each part of the curve.We divide 
the area into n equal segments of width Δx. 
Simpson's rule can be derived by approximating the integrand f (x) (in blue) 
by the quadratic interpolant P(x) (in red). 

👁 graph

In order to integrate any function f(x) in the interval (a, b), follow the steps given below:
1.Select a value for n, which is the number of parts the interval is divided into. 
2.Calculate the width, h = (b-a)/n 
3.Calculate the values of x0 to xn as x0 = a, x1 = x0 + h, .....xn-1 = xn-2 + h, xn = b. 
Consider y = f(x). Now find the values of y(y0 to yn) for the corresponding x(x0 to xn) values. 
4.Substitute all the above found values in the Simpson's Rule Formula to calculate the integral value.
Approximate value of the integral can be given by Simpson's Rule: 

Note : In this rule, n must be EVEN.
Application :
It is used when it is very difficult to solve the given integral mathematically. 
This rule gives approximation easily without actually knowing the integration rules.
Example : 

Evaluate logx dx within limit 4 to 5.2.

First we will divide interval into six equal 
parts as number of interval should be even.

x : 4 4.2 4.4 4.6 4.8 5.0 5.2
logx : 1.38 1.43 1.48 1.52 1.56 1.60 1.64

Now we can calculate approximate value of integral
using above formula:
 = h/3[( 1.38 + 1.64) + 4 * (1.43 + 1.52 + 
 1.60 ) +2 *(1.48 + 1.56)]
 = 1.84
Hence the approximation of above integral is 
1.827 using Simpson's 1/3 rule. 

Output: 

1.827847

Time Complexity: O(n)
Auxiliary Space: O(1)