ELI5: Explain Like I'm 5

Cholesky decomposition

Okay kiddo, so let's say you have a big square matrix, which is just a list of numbers arranged in rows and columns. Now, this matrix might seem really confusing and hard to work with, but there's a special technique called Cholesky Decomposition that helps break it down into simpler parts.

Think of it like building a tower out of blocks. Each block is a little piece of the matrix, and we want to take apart the matrix block by block until we can understand how it's put together. Cholesky Decomposition helps us do this by finding a special kind of block called a "lower triangular matrix".

A lower triangular matrix just means a block where all the numbers above the diagonal (which is just a line from the top left corner to the bottom right corner) are zero. So it looks like a staircase made of numbers. We can use this special kind of block to represent part of the matrix, and then we can use some math tricks to figure out the other parts.

The way we find the lower triangular matrix is by looking at the matrix itself and trying to "factorize" it, which means writing it as a product of two smaller matrices. We use some fancy math formulas to do this, but basically we're just trying to break it down into simpler pieces.

Once we've found the lower triangular matrix, we can use it to solve equations involving the matrix. So if we have some complicated math problem that involves the matrix, we can break it down into smaller parts using Cholesky Decomposition and then solve those parts one by one.

So there you have it, buddy! Cholesky Decomposition is just a way of breaking down a big matrix into simpler parts using a special kind of block called a lower triangular matrix. It helps us solve complicated math problems involving the matrix by breaking them down into smaller parts.