Obsidian Knowledge Management MCP Server

---
Created: 2025-08-22
Type: Zettel
aliases: 
References: 
Links:
  - "[[Matrices]]"
  - "[[Matrix multiplication]]"
tags:
  - MATH31AH
---
- The identity [[Matrices|matrix]] plays the same role as the number 1 in [[Matrix multiplication|matrix multiplication]] 
- It is a square ($n \times n$) matrix with 1's along the main diagonal (from top left to bottom right)
	- It is denoted as $I_{n} \in M_{n \times n}(\mathbb{R})$
> 
$$
I_{2} = \begin{bmatrix}
1 & 0  \\
0 & 1
\end{bmatrix} \text{ and }
I_{4} = \begin{bmatrix}
1 & 0 & 0 & 0 \\
0 & 1 & 0 & 0 \\
0 & 0 & 1 & 0 \\
0 & 0 & 0 & 1 \\
\end{bmatrix}
$$
- You can also write this as $(a_{ij})_{n,n}$ where $a_{ij} = 1$ if $i = j$ and $a_{ij} = 0$ if $i \neq j$