Square Matrix
From the book
Chapter 2: Matrix. In the chapter mind map this icon labels Square. The discussion below is excerpted and lightly edited from § Theorem: Left Inverse Equals Right Inverse for Square Matrices in Mathematics for AI and Machine Learning.
Let $A \in \mathbb{R}^{N \times N}$. If there exists a matrix $B \in \mathbb{R}^{N \times N}$ such that $AB = I_{N \times N}$, then $A$ is invertible, $B = A^{-1}$, and consequently $BA = I_{N \times N}$.
In particular, for any invertible matrix $A$, $AA^{-1} = A^{-1}A = I_{N \times N}$.
What this drawing shows
What you see. Matrix with the same number of rows and columns, representing endomorphisms and eigenvalue problems.
In the mind map. Chapter 2 — Square. See From the book above for definitions, figures, and worked examples.
Where to read next
Read the full definitions, figures, and worked examples in Chapter 2: Matrix — see the mind-map node Square.