allwpilib/upstream_utils/sleipnir_patches/0002-Downgrade-to-Eigen-5.0.1.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Tyler Veness <calcmogul@gmail.com>
Date: Sun, 26 Apr 2026 16:56:01 -0700
Subject: [PATCH 2/2] Downgrade to Eigen 5.0.1

---
 include/sleipnir/autodiff/variable.hpp        | 20 ++++++--
 include/sleipnir/autodiff/variable_block.hpp  | 30 +++++++++---
 include/sleipnir/autodiff/variable_matrix.hpp | 46 ++++++++++++-------
 3 files changed, 69 insertions(+), 27 deletions(-)

diff --git a/include/sleipnir/autodiff/variable.hpp b/include/sleipnir/autodiff/variable.hpp
index ad8baa3b58047f5257c210b88446324cca121d4a..6c692cbe113a3aaf7f02727260ed0b6d1f4a3c23 100644
--- a/include/sleipnir/autodiff/variable.hpp
+++ b/include/sleipnir/autodiff/variable.hpp
@@ -733,7 +733,11 @@ auto make_constraints(LHS&& lhs, RHS&& rhs) {
   for (int row = 0; row < rhs.rows(); ++row) {
     for (int col = 0; col < rhs.cols(); ++col) {
       // Make right-hand side zero
-      constraints.emplace_back(lhs - rhs[row, col]);
+      if constexpr (EigenMatrixLike<RHS>) {
+        constraints.emplace_back(lhs - rhs(row, col));
+      } else {
+        constraints.emplace_back(lhs - rhs[row, col]);
+      }
     }
   }
 
@@ -749,7 +753,11 @@ auto make_constraints(LHS&& lhs, RHS&& rhs) {
   for (int row = 0; row < lhs.rows(); ++row) {
     for (int col = 0; col < lhs.cols(); ++col) {
       // Make right-hand side zero
-      constraints.emplace_back(lhs[row, col] - rhs);
+      if constexpr (EigenMatrixLike<LHS>) {
+        constraints.emplace_back(lhs(row, col) - rhs);
+      } else {
+        constraints.emplace_back(lhs[row, col] - rhs);
+      }
     }
   }
 
@@ -767,7 +775,13 @@ auto make_constraints(LHS&& lhs, RHS&& rhs) {
   for (int row = 0; row < lhs.rows(); ++row) {
     for (int col = 0; col < lhs.cols(); ++col) {
       // Make right-hand side zero
-      constraints.emplace_back(lhs[row, col] - rhs[row, col]);
+      if constexpr (!EigenMatrixLike<LHS> && !EigenMatrixLike<RHS>) {
+        constraints.emplace_back(lhs[row, col] - rhs[row, col]);
+      } else if constexpr (!EigenMatrixLike<LHS> && EigenMatrixLike<RHS>) {
+        constraints.emplace_back(lhs[row, col] - rhs(row, col));
+      } else if constexpr (EigenMatrixLike<LHS> && !EigenMatrixLike<RHS>) {
+        constraints.emplace_back(lhs(row, col) - rhs[row, col]);
+      }
     }
   }
 
diff --git a/include/sleipnir/autodiff/variable_block.hpp b/include/sleipnir/autodiff/variable_block.hpp
index 55cafb5d48afff2dbdff07516d85759180ef74c7..cf1b2a37614f748db679071df1780a569527983f 100644
--- a/include/sleipnir/autodiff/variable_block.hpp
+++ b/include/sleipnir/autodiff/variable_block.hpp
@@ -161,7 +161,7 @@ class VariableBlock : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        (*this)[row, col] = values[row, col];
+        (*this)[row, col] = values(row, col);
       }
     }
 
@@ -178,7 +178,7 @@ class VariableBlock : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        (*this)[row, col].set_value(values[row, col]);
+        (*this)[row, col].set_value(values(row, col));
       }
     }
   }
@@ -438,7 +438,11 @@ class VariableBlock : public SleipnirBase {
       for (int j = 0; j < rhs.cols(); ++j) {
         Variable sum{Scalar(0)};
         for (int k = 0; k < cols(); ++k) {
-          sum += lhs_old_row[k] * rhs[k, j];
+          if constexpr (EigenMatrixLike<decltype(rhs)>) {
+            sum += lhs_old_row[k] * rhs(k, j);
+          } else {
+            sum += lhs_old_row[k] * rhs[k, j];
+          }
         }
         (*this)[i, j] = sum;
       }
@@ -470,7 +474,11 @@ class VariableBlock : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        (*this)[row, col] /= rhs[0, 0];
+        if constexpr (EigenMatrixLike<decltype(rhs)>) {
+          (*this)[row, col] /= rhs(0, 0);
+        } else {
+          (*this)[row, col] /= rhs[0, 0];
+        }
       }
     }
 
@@ -500,7 +508,11 @@ class VariableBlock : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        (*this)[row, col] += rhs[row, col];
+        if constexpr (EigenMatrixLike<decltype(rhs)>) {
+          (*this)[row, col] += rhs(row, col);
+        } else {
+          (*this)[row, col] += rhs[row, col];
+        }
       }
     }
 
@@ -532,7 +544,11 @@ class VariableBlock : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        (*this)[row, col] -= rhs[row, col];
+        if constexpr (EigenMatrixLike<decltype(rhs)>) {
+          (*this)[row, col] -= rhs(row, col);
+        } else {
+          (*this)[row, col] -= rhs[row, col];
+        }
       }
     }
 
@@ -612,7 +628,7 @@ class VariableBlock : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        result[row, col] = value(row, col);
+        result(row, col) = value(row, col);
       }
     }
 
diff --git a/include/sleipnir/autodiff/variable_matrix.hpp b/include/sleipnir/autodiff/variable_matrix.hpp
index 72559959cfc4cb38e099a2268c66088ea19551f5..59393e2eabdf9107de8ff6b554a48d83f8b9ef1e 100644
--- a/include/sleipnir/autodiff/variable_matrix.hpp
+++ b/include/sleipnir/autodiff/variable_matrix.hpp
@@ -154,7 +154,7 @@ class VariableMatrix : public SleipnirBase {
     m_storage.reserve(values.rows() * values.cols());
     for (int row = 0; row < values.rows(); ++row) {
       for (int col = 0; col < values.cols(); ++col) {
-        m_storage.emplace_back(values[row, col]);
+        m_storage.emplace_back(values(row, col));
       }
     }
   }
@@ -262,7 +262,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < values.rows(); ++row) {
       for (int col = 0; col < values.cols(); ++col) {
-        (*this)[row, col] = values[row, col];
+        (*this)[row, col] = values(row, col);
       }
     }
 
@@ -293,7 +293,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < values.rows(); ++row) {
       for (int col = 0; col < values.cols(); ++col) {
-        (*this)[row, col].set_value(values[row, col]);
+        (*this)[row, col].set_value(values(row, col));
       }
     }
   }
@@ -573,7 +573,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < result.rows(); ++row) {
       for (int col = 0; col < result.cols(); ++col) {
-        result[row, col] = lhs[row, col] * rhs;
+        result[row, col] = lhs(row, col) * rhs;
       }
     }
 
@@ -608,7 +608,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < result.rows(); ++row) {
       for (int col = 0; col < result.cols(); ++col) {
-        result[row, col] = rhs[row, col] * lhs;
+        result[row, col] = rhs(row, col) * lhs;
       }
     }
 
@@ -644,7 +644,11 @@ class VariableMatrix : public SleipnirBase {
       for (int j = 0; j < rhs.cols(); ++j) {
         Variable sum{Scalar(0)};
         for (int k = 0; k < cols(); ++k) {
-          sum += lhs_old_row[k] * rhs[k, j];
+          if constexpr (EigenMatrixLike<decltype(rhs)>) {
+            sum += lhs_old_row[k] * rhs(k, j);
+          } else {
+            sum += lhs_old_row[k] * rhs[k, j];
+          }
         }
         (*this)[i, j] = sum;
       }
@@ -679,7 +683,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < result.rows(); ++row) {
       for (int col = 0; col < result.cols(); ++col) {
-        result[row, col] = lhs[row, col] / rhs;
+        result[row, col] = lhs(row, col) / rhs;
       }
     }
 
@@ -751,7 +755,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < result.rows(); ++row) {
       for (int col = 0; col < result.cols(); ++col) {
-        result[row, col] = lhs[row, col] + rhs[row, col];
+        result[row, col] = lhs(row, col) + rhs[row, col];
       }
     }
 
@@ -771,7 +775,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < result.rows(); ++row) {
       for (int col = 0; col < result.cols(); ++col) {
-        result[row, col] = lhs[row, col] + rhs[row, col];
+        result[row, col] = lhs[row, col] + rhs(row, col);
       }
     }
 
@@ -807,7 +811,11 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        (*this)[row, col] += rhs[row, col];
+        if constexpr (EigenMatrixLike<decltype(rhs)>) {
+          (*this)[row, col] += rhs(row, col);
+        } else {
+          (*this)[row, col] += rhs[row, col];
+        }
       }
     }
 
@@ -843,7 +851,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < result.rows(); ++row) {
       for (int col = 0; col < result.cols(); ++col) {
-        result[row, col] = lhs[row, col] - rhs[row, col];
+        result[row, col] = lhs(row, col) - rhs[row, col];
       }
     }
 
@@ -863,7 +871,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < result.rows(); ++row) {
       for (int col = 0; col < result.cols(); ++col) {
-        result[row, col] = lhs[row, col] - rhs[row, col];
+        result[row, col] = lhs[row, col] - rhs(row, col);
       }
     }
 
@@ -899,7 +907,11 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        (*this)[row, col] -= rhs[row, col];
+        if constexpr (EigenMatrixLike<decltype(rhs)>) {
+          (*this)[row, col] -= rhs(row, col);
+        } else {
+          (*this)[row, col] -= rhs[row, col];
+        }
       }
     }
 
@@ -992,7 +1004,7 @@ class VariableMatrix : public SleipnirBase {
 
     for (int row = 0; row < rows(); ++row) {
       for (int col = 0; col < cols(); ++col) {
-        result[row, col] = value(row, col);
+        result(row, col) = value(row, col);
       }
     }
 
@@ -1617,14 +1629,14 @@ VariableMatrix<Scalar> solve(const VariableMatrix<Scalar>& A,
     MatrixXv eigen_A{A.rows(), A.cols()};
     for (int row = 0; row < A.rows(); ++row) {
       for (int col = 0; col < A.cols(); ++col) {
-        eigen_A[row, col] = A[row, col];
+        eigen_A(row, col) = A[row, col];
       }
     }
 
     MatrixXv eigen_B{B.rows(), B.cols()};
     for (int row = 0; row < B.rows(); ++row) {
       for (int col = 0; col < B.cols(); ++col) {
-        eigen_B[row, col] = B[row, col];
+        eigen_B(row, col) = B[row, col];
       }
     }
 
@@ -1633,7 +1645,7 @@ VariableMatrix<Scalar> solve(const VariableMatrix<Scalar>& A,
     VariableMatrix<Scalar> X{detail::empty, A.cols(), B.cols()};
     for (int row = 0; row < X.rows(); ++row) {
       for (int col = 0; col < X.cols(); ++col) {
-        X[row, col] = eigen_X[row, col];
+        X[row, col] = eigen_X(row, col);
       }
     }