From e322ab8e4629634077880ec215330a1511ba6cd7 Mon Sep 17 00:00:00 2001
From: Tyler Veness <calcmogul@gmail.com>
Date: Mon, 28 Aug 2023 15:10:42 -0700
Subject: [PATCH] [wpimath] Fix docs for DARE ABQRN stabilizability check (NFC)
 (#5579)

---
 wpimath/src/main/java/edu/wpi/first/math/DARE.java       | 4 ++--
 wpimath/src/main/java/edu/wpi/first/math/WPIMathJNI.java | 4 ++--
 wpimath/src/main/native/include/frc/DARE.h               | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/wpimath/src/main/java/edu/wpi/first/math/DARE.java b/wpimath/src/main/java/edu/wpi/first/math/DARE.java
index d9d0b55877..af2a0217af 100644
--- a/wpimath/src/main/java/edu/wpi/first/math/DARE.java
+++ b/wpimath/src/main/java/edu/wpi/first/math/DARE.java
@@ -90,7 +90,7 @@ public final class DARE {
    * <ul>
    *   <li>Q − NR⁻¹Nᵀ isn't symmetric positive semidefinite
    *   <li>R isn't symmetric positive definite
-   *   <li>The (A, B) pair isn't stabilizable
+   *   <li>The (A − BR⁻¹Nᵀ, B) pair isn't stabilizable
    *   <li>The (A, C) pair where Q = CᵀC isn't detectable
    * </ul>
    *
@@ -199,7 +199,7 @@ public final class DARE {
    * @return Solution of DARE.
    * @throws IllegalArgumentException if Q − NR⁻¹Nᵀ isn't symmetric positive semidefinite.
    * @throws IllegalArgumentException if R isn't symmetric positive definite.
-   * @throws IllegalArgumentException if the (A, B) pair isn't stabilizable.
+   * @throws IllegalArgumentException if the (A − BR⁻¹Nᵀ, B) pair isn't stabilizable.
    * @throws IllegalArgumentException if the (A, C) pair where Q = CᵀC isn't detectable.
    */
   public static <States extends Num, Inputs extends Num> Matrix<States, States> dare(
diff --git a/wpimath/src/main/java/edu/wpi/first/math/WPIMathJNI.java b/wpimath/src/main/java/edu/wpi/first/math/WPIMathJNI.java
index a13726ffb7..71046c8c58 100644
--- a/wpimath/src/main/java/edu/wpi/first/math/WPIMathJNI.java
+++ b/wpimath/src/main/java/edu/wpi/first/math/WPIMathJNI.java
@@ -109,7 +109,7 @@ public final class WPIMathJNI {
    * <ul>
    *   <li>Q − NR⁻¹Nᵀ isn't symmetric positive semidefinite
    *   <li>R isn't symmetric positive definite
-   *   <li>The (A, B) pair isn't stabilizable
+   *   <li>The (A − BR⁻¹Nᵀ, B) pair isn't stabilizable
    *   <li>The (A, C) pair where Q = CᵀC isn't detectable
    * </ul>
    *
@@ -195,7 +195,7 @@ public final class WPIMathJNI {
    * @param S Array storage for DARE solution.
    * @throws IllegalArgumentException if Q − NR⁻¹Nᵀ isn't symmetric positive semidefinite.
    * @throws IllegalArgumentException if R isn't symmetric positive definite.
-   * @throws IllegalArgumentException if the (A, B) pair isn't stabilizable.
+   * @throws IllegalArgumentException if the (A − BR⁻¹Nᵀ, B) pair isn't stabilizable.
    * @throws IllegalArgumentException if the (A, C) pair where Q = CᵀC isn't detectable.
    */
   public static native void dareABQRN(
diff --git a/wpimath/src/main/native/include/frc/DARE.h b/wpimath/src/main/native/include/frc/DARE.h
index 9a9e0fa22e..cc7c141d6f 100644
--- a/wpimath/src/main/native/include/frc/DARE.h
+++ b/wpimath/src/main/native/include/frc/DARE.h
@@ -213,7 +213,7 @@ performance. The solver may hang if any of the following occur:
 <ul>
   <li>Q − NR⁻¹Nᵀ isn't symmetric positive semidefinite</li>
   <li>R isn't symmetric positive definite</li>
-  <li>The (A, B) pair isn't stabilizable</li>
+  <li>The (A − BR⁻¹Nᵀ, B) pair isn't stabilizable</li>
   <li>The (A, C) pair where Q = CᵀC isn't detectable</li>
 </ul>
 Only use this function if you're sure the preconditions are met.
@@ -336,7 +336,7 @@ J = Σ [uₖ] [0 R][uₖ] ΔT
 @throws std::invalid_argument if Q − NR⁻¹Nᵀ isn't symmetric positive
   semidefinite.
 @throws std::invalid_argument if R isn't symmetric positive definite.
-@throws std::invalid_argument if the (A, B) pair isn't stabilizable.
+@throws std::invalid_argument if the (A − BR⁻¹Nᵀ, B) pair isn't stabilizable.
 @throws std::invalid_argument if the (A, C) pair where Q = CᵀC isn't detectable.
 */
 template <int States, int Inputs>