---
tag: 0KCE8CG86P
kind: concept
name: Idempotent matrix
aliases: [projection-matrix]
msc: [15A99]
sources:
  - url: https://en.wikipedia.org/wiki/Idempotent_matrix
    locator: lead section
same_as:
  wikidata: Q3751720
  wikipedia: Idempotent matrix
---

## Summary

An idempotent matrix is a square matrix that is equal to its own square.