Finite-difference frequency-domain

Imagine you're playing a game where you need to solve a puzzle with different colors on it. You have a pencil and a paper to help you figure out the solution. You can use your pencil to write on the paper, draw shapes, or color in certain parts of the puzzle.

Now, let's say you want to find out how the puzzle would look like if you changed the colors. You could redraw the entire puzzle with the new colors, but that would take a lot of time and effort. Instead, what you can do is use the finite-difference frequency-domain method, which is kind of like a shortcut.

The "finite-difference" part of the method refers to the fact that we divide the puzzle into small pieces or "finite differences." We can think of these pieces as little boxes that make up the whole puzzle. Each box has a certain color, which we can represent with a number.

The "frequency-domain" part of the method comes from the idea that we can analyze the puzzle using different frequencies. Think of frequencies like the notes on a piano. Some notes are higher, while others are lower. Similarly, by looking at the puzzle through different frequencies, we can see different patterns and details.

So, to use the finite-difference frequency-domain method, we first divide the puzzle into little boxes, each with a number representing a certain color. Then, we analyze the puzzle using different frequencies to see different patterns and details. This method helps us save time and effort by avoiding the need to manually redraw the puzzle every time we want to change the colors.