From 8889c13fa72435ff8cfc468ae155cca95a5c4768 Mon Sep 17 00:00:00 2001
From: Taylor Howell <taylorhowell@google.com>
Date: Wed, 28 Jan 2026 10:17:36 -0800
Subject: [PATCH] MuJoCo Warp documentation: Inertia matrix factorization

PiperOrigin-RevId: 862290080
Change-Id: I7acd30f1fff5cca95ca1139f71710cab5c493561
---
 doc/mjwarp/index.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/doc/mjwarp/index.rst b/doc/mjwarp/index.rst
index 938a8180..e8ebdc26 100644
--- a/doc/mjwarp/index.rst
+++ b/doc/mjwarp/index.rst
@@ -668,3 +668,12 @@ Warmstart
 If warmstarts are not :ref:`disabled <option-flag-warmstart>`, the MJWarp solver warmstart always initializes the
 acceleration with ``qacc_warmstart``. In contrast, MuJoCo performs a comparison between ``qacc_smooth`` and
 ``qacc_warmstart`` to determine which one is utilized for the initialization.
+
+Inertia matrix factorization
+----------------------------
+
+When using dense computation, MJWarp's factorization of the inertia matrix ``qLD`` is computed with Warp's ``L'L``
+Cholesky factorization
+`wp.tile_cholesky <https://nvidia.github.io/warp/language_reference/_generated/warp._src.lang.tile_cholesky.html>`__
+and the result is not expected to match MuJoCo's corresponding field because a different reverse-mode ``L'DL`` routine
+:ref:`mj_factorM` is utilized.