Enter the function, lower limit, upper limit, and number of intervals to approximate the integral using Simpson's rule.

## Simpson's Rule Calculation Formula

The following formula is used to approximate the integral of a function.

Integral ≈ (h / 3) * [f(a) + 4 * Σ f(a + (2k-1)h) + 2 * Σ f(a + 2kh) + f(b)]

Variables:

- f(x) is the function to be integrated
- a and b are the lower and upper limits of integration, respectively
- n is the number of intervals (must be even)
- h = (b - a) / n
- Σ denotes the summation notation

Simpson's rule is a method for numerical integration, the numerical approximation of definite integrals. Specifically, it is the composite Simpson's rule. Simpson's rule also corresponds to the exact evaluation of definite integrals for all polynomials up to and including the third degree.

## What is Simpson's Rule?

Simpson's rule is a method for approximating the definite integral of a function. This method is particularly useful when the exact integration is difficult or impossible to perform analytically. The rule approximates the integral by dividing the area under the curve into a series of parabolic segments, which can be more accurate than other numerical methods like the trapezoidal rule.

## How to Calculate Using Simpson's Rule?

The following steps outline how to use Simpson's rule to approximate an integral:

- Determine the function f(x) to be integrated.
- Choose the interval [a, b] over which to integrate.
- Select the number of intervals n (must be even).
- Calculate the width of each interval h = (b - a) / n.
- Apply Simpson's rule formula to approximate the integral.
- Verify the accuracy of your result with the calculator above.

**Example Problem:**

Use the following variables as an example problem to test your knowledge:

Function: f(x) = x^2 + 3*x + 2

Lower Limit: a = 1

Upper Limit: b = 4

Number of Intervals: n = 6

## FAQ

**1. What is numerical integration?**

Numerical integration refers to the process of calculating the integral of a function using numerical methods rather than analytical methods. This is useful for functions that are difficult to integrate by hand.

**2. Why use Simpson's rule over other methods?**

Simpson's rule often provides more accurate results compared to other numerical methods like the trapezoidal rule, especially when the function being integrated is smooth and can be well-approximated by parabolas over small intervals.

**3. What are the limitations of Simpson's rule?**

Simpson's rule requires the number of intervals to be even, and its accuracy can be reduced for functions that are not smooth or have high variability over the integration interval.

**4. Can this calculator be used for different functions?**

Yes, you can input any valid mathematical function into the calculator to approximate its integral using Simpson's rule.

**5. Is the calculator accurate?**

The calculator provides an estimate of the integral based on Simpson's rule. While it is generally accurate, for highly precise calculations, more advanced numerical methods or analytical integration might be needed.