Python program for integration using simpsons 1/3 - Rule

The above rule is applicable only when n=6k (multiple of 6 ) ,we just have to find the value of y corresponding to (value) of x ,given by y=f(x).

Now for implementation of this formula in the program ,we need to first find the value's of y corresponding to each x :
for that we have to convert the entered string by the user to a python expression for calculation of required values and then substituting in simpson's formula.

The conversion of string to python expression can be achieved by using lambda function:

ep=input("Expression ")
f = lambda x: eval(ep)

here, the input string is first stored in ep  and then converted to python expression (function) using lambda.

SOURCE CODE:

# SIMPSONS 1/3 -RULE
# SOURCE: QXCODING.COM / JATIN YADAV
if __name__ == '__main__':
    ep=input("Expression ")
    f = lambda x: eval(ep)
    a, b = map(int, input("limits ").rstrip().split())
    n = int(input("number of strips for accuracy "))
    if (n % 2 != 0):
        print("strips =2k")
        exit(0)
    h = (b - a) / n
    sum = 0
    for i in range(n + 1):
        y = f(h*i)
        print(y)
        if i in [0, n]:
            sum += y
        elif i % 2 == 0:
            sum += 2 * y
        else:
            sum += 4 * y
    print("value=", (h / 3) * (sum))

if any doubts or queries please comment