Computing Pi in Matlab - A Comprehensive Guide for Engineers and Data Scientists

This article will thoroughly explain how to calculate the approximate value of pi using Matlab, a powerful programming language widely used in scientific and engineering fields. By understanding this …

Updated October 12, 2023

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This article will thoroughly explain how to calculate the approximate value of pi using Matlab, a powerful programming language widely used in scientific and engineering fields. By understanding this process, you’ll acquire valuable insight into numerical computations as well as Matlab’s functionality for solving complex mathematical problems. Moreover, we will provide code samples throughout this tutorial to demonstrate key concepts related to Matlab programming while computing pi.


Pi (π), also known as Archimedes' constant, is a fundamental irrational and transcendental number. It plays an essential role in numerous scientific disciplines including geometry, trigonometry, mathematical modeling, and engineering designs. Obtaining the precise value of pi can be complex due to its infinite digits, so we often resort to approximations. In this article, we will focus on calculating approximate values of pi using Matlab – a highly regarded software for technical computing and visualization that supports an extensive range of data analysis and algorithm development applications.

Matlab’s pi() Function

One of the simplest ways to compute pi in Matlab is by utilizing its built-in pi() function, which returns the exact value of pi as 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803440246576… As shown below, you can simply type pi() in the Matlab command window and press Enter to display pi’s exact value:

>> pi()
ans = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803440246576...

Although this approach provides the exact value of pi, working with infinite decimal places is inconvenient for most practical applications. A more efficient approach is to compute an approximate value of pi with finite decimal places and customizable precision levels.

Computing Approximate Pi Values in Matlab

To calculate pi approximations within a specified number of digits, you can use the round() function, which returns its input rounded to the nearest integer or the given tolerance level. Matlab provides two functions that are particularly useful for generating approximate values of pi:

  1. pi_approx(): This function calculates an approximate value of pi using the Archimedes' method with a specified number of iterations. The formula used by this function is 4 * sum(1 / (2n - 1)), where n varies from 1 to the given limit. For example, using pi_approx(10) will result in an approximate pi value calculated up to 10 iterations.

  2. circleArea(): This function computes the area of a circle with a given radius. You can use this function along with Matlab’s built-in pi() function to derive an approximate pi value as well.

Let’s explore both methods step by step.

Using pi_approx() Function

The pi_approx() function employs Archimedes' method, a recursive formula that estimates pi by successively approximating the circumference of a circle and its diameter (area). As mentioned before, this function uses the formula: 4 * sum(1 / (2n - 1)). Here is how you can use it in your Matlab code:

pi_approx_value = pi_approx(10)   % Calculate an approximate value of pi using Archimedes' method with 10 iterations.
% The resulting pi_approx_value will be accurate up to the 10th decimal place.

Using circleArea() Function

Another approach is utilizing Matlab’s circleArea() function, which calculates the area of a circle given its radius:

% Calculate the radius of a circle with a specified area (e.g., 1)
radius = sqrt(circleArea(1))   % Use square root to convert from area to radius
% The resulting radius will be equal to the inverse of pi, since pi * r^2 = A (the area)
pi_approx_value = radius^2 / circleArea(1)  % Compute an approximation for pi by squaring the radius and dividing it with the original area.

In the example above, we are using a simple circle with an area of one (A=1) to estimate pi. By varying the area, you can obtain approximations at different levels of precision. Keep in mind that this method is less efficient compared to pi_approx(), as it requires more calculations due to the additional step of computing a specific radius for a given area.

Combining Both Methods

You can also combine these two approaches, which may yield even more accurate approximations depending on the chosen number of iterations in the Archimedes' method and the precision level for computing areas with the circleArea() function. For instance:

% Calculate an approximate value of pi using both methods and compare results
approx_pi1 = pi_approx(5)   % Use pi_approx() with 5 iterations.
approx_pi2 = pi_approx(8)   % Use pi_approx() with 8 iterations.
radius1 = sqrt(circleArea(1))
area1 = circleArea(1);
pi_approx_value = radius1^2 / area1;  % Calculate an approximation for pi using the circleArea() method and the radius derived from the given area.

In conclusion, Matlab provides multiple ways to compute pi approximations for various practical purposes. You can choose between built-in functions such as pi_approx(), circleArea(), or a combination of both methods depending on your needs. Remember to tailor the precision levels according to your specific use cases and keep experimenting with different techniques to fine-tune your calculations.