Understanding Different Types of Distance in Math
A look into how various distance measurements impact shapes and data.
― 7 min read
Table of Contents
- What is Distance Anyway?
- Time to Get Fancy: Introducing the Minkowski Distance
- Why Do Different Distances Matter?
- Playing with Shapes in Space
- Squigonometric Functions: A Playful Name
- What’s the Deal with Area and Length?
- A Slice of Fun: The Rectangle Rule
- Exploring High Dimensions: What’s Going On?
- Sampling: A Fun Way to Play with Points
- The Big Confusion: The Borel-Kolmogorov Paradox
- Wrapping It All Up
- Original Source
- Reference Links
When we talk about how far apart things are, we usually think of measuring distances, right? It’s straight forward for everyday life. You know, like figuring out how far your favorite pizza place is or how far away your friend lives. In the world of math, this idea gets a bit more complicated, especially when we throw in different ways to measure those distances.
What is Distance Anyway?
Distance, in math, has different names depending on how you measure it. You’ve probably heard of “Manhattan Distance” when we talk about streets on a grid, where you can only move in straight lines up and down, or side to side. Think of it as if you are a taxi in a city that’s built like a grid. You can’t cut across blocks; you need to go around.
Then there's the "Euclidean Distance," which is just a fancy way of saying the straight line between two points. It’s what you’d use if you were a bird flying from one place to another.
And finally, there’s something called "Chebyshev distance." This one is really fun. It’s all about how far away you are if you can move in any direction, but you want to know the maximum distance you have to move in one step. Imagine you’re playing on a chessboard and you want to know how far away the queen is from another piece.
Time to Get Fancy: Introducing the Minkowski Distance
Now, let’s introduce a fancy term, the “Minkowski distance.” This is a type of distance that can be adapted based on what you need. It can take on the forms we've already talked about (the Manhattan, Euclidean, and Chebyshev Distances), but it can also be other things depending on a number (we'll call it p).
So, depending on the number you choose, the Minkowski distance can change its flavor! If you pick p = 1, it becomes Manhattan distance. For p = 2, it’s straight-up Euclidean distance. And if you go with p = infinity, you get Chebyshev distance.
Why Do Different Distances Matter?
You might wonder, why should we care about these different types of distances? Well, in the world of data and machine learning-where computers learn and make decisions based on data-these distances help in making sense of all that data. They help to determine how similar or different things are from one another.
For example, if you want to find out how similar two pictures are, you can use these distances to calculate how far apart the pixels in the images are. The closer they are, the more similar the images are, right?
Playing with Shapes in Space
Let’s get back to shapes for a moment. Imagine a space with all sorts of interesting shapes. When you look at how distances work in different shapes, you need to think of things like circles and squares, or even more complicated shapes like ellipses.
In 2D, if you take a circle defined by any of these distances, it would look different depending on the distance type you're using. The p you choose can change how “fat” or “skinny” the circle appears.
So, when we talk about the "2-ball" (which is just a fancy term for a circle), it takes on different forms depending on whether you’re using Manhattan, Euclidean, or Chebyshev distances.
Squigonometric Functions: A Playful Name
To help us work with these distances, we’ve got something called squigonometric functions. Yes, squigonometric! Imagine it’s like sine and cosine, but with a twist! These help define those shapes in our distance world, especially when we’re dealing with circles.
Think of them as a tool for helping us navigate through the shapes and understanding their properties. These functions allow us to parameterize-or break down-circles into manageable chunks, making them easier to work with.
What’s the Deal with Area and Length?
When it comes to measuring areas and lengths, you’ll find that the type of distance you use matters here too!
In a 2D space, if you want to measure the area of a circle or the length of a curve, the distance type will change the outcome. This is especially true if you’re comparing different shapes. For example, if you have a circle and a square of the same area, figuring out the length depends on how you’re measuring distance.
Now, if we focus on the first quadrant of a circle, you can think of it like the slice of a pie. The area and the length of the curve can change based on what measure you decide to use.
A Slice of Fun: The Rectangle Rule
Imagine you have a rectangle. The area of that rectangle doesn’t change, no matter what distance method you use. It’s always the same, which is great! But when you deal with curves, things can get tricky.
You can think of a curve as a wiggly line instead of a straight one, and when you try to measure it, the distance type you select will change how you compute that length. It can be a bit wild, like trying to measure how long a snake is using different methods.
Exploring High Dimensions: What’s Going On?
Now, if you think area and length are interesting in 2D, wait until you hear about 3D! When you enter the world of 3D (think cubes and spheres), the distance concepts still hold, but they become even more complex.
For example, if you have a 3D ball, the volume doesn’t depend on how you measure distances, but the surface will! That’s where things can get confusing. It’s like comparing apples and oranges.
Sampling: A Fun Way to Play with Points
Sampling is a cool way to generate points within a given shape, so you can explore its properties! Imagine you’re using a computer program to randomly pick points inside a circle or on the surface. The idea is to get a good mix of points that fairly represents that shape.
You can do this using different methods and, of course, which distance type you choose will affect how well you fill up that circle or how many points you get on the surface.
The Big Confusion: The Borel-Kolmogorov Paradox
Here’s where it gets a bit mind-bending. There's a bit of a snag that scientists and mathematicians often talk about called the Borel-Kolmogorov paradox. It’s a fancy way of saying that when you take samples from shapes, the result can sometimes be surprising.
Imagine you’re sampling from a uniform distribution over a sphere. You would think it’s all equal, right? Well, when you get to the edges, the reality gets complicated. The distribution you get at the ends can vary from what you expect at the center!
When you start to restrict your distribution to certain parts, like a line going from the top to the bottom of the sphere, you might find that the values aren’t as balanced as you thought. It’s like thinking you can slice a cake evenly, but it turns out, some slices are much bigger than others!
Wrapping It All Up
So, whether you’re trying to measure distances, compare shapes, or sample from them, the world of metrics (that’s just a fancy word for distance measurement) is a fascinating place! Each method, whether it’s the Minkowski distance or something else, adds a flavor to the math that scientists, engineers, and even pizza lovers can enjoy.
By keeping it simple and using fun tools like squigonometric functions, you can navigate through this complex world with ease. Remember, math doesn’t have to be scary. It can be like a fun puzzle waiting to be solved!
Title: Why the p-norms $p{=}1$, $p{=}2$ and $p{=}\infty$ are so special? An answer based on spatial uniformity
Abstract: Among all metrics based on p-norms, the Manhattan (p=1), euclidean (p=2) and Chebyshev distances (p=infinity) are the most widely used for their interpretability, simplicity and technical convenience. But these are not the only arguments for the ubiquity of these three p-norms. This article proves that there is a volume-surface correspondence property that is unique to them. More precisely, it is shown that sampling uniformly from the volume of an n-dimensional p-ball and projecting to its surface is equivalent to directly sampling uniformly from its surface if and only if p is 1, 2 or infinity. Sampling algorithms and their implementations in Python are also provided.
Authors: Carlos Pinzón
Last Update: 2024-11-11 00:00:00
Language: English
Source URL: https://arxiv.org/abs/2411.13567
Source PDF: https://arxiv.org/pdf/2411.13567
Licence: https://creativecommons.org/licenses/by/4.0/
Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.
Thank you to arxiv for use of its open access interoperability.