[wpimath] Clean up Eigen usage

* Replace Matrix<> with Vector<> where vectors are explicitly intended.
  I found these via `rg "Eigen::Matrix<double, \w+, 1>"`.
* Pass all Eigen matrices by const reference. I found these via `rg
  "\(Eigen"` on main (the initializer list constructors make more false
  positives).
* Replace MakeMatrix() and operator<< usage with initializer list
  constructors. I found these via `rg MakeMatrix` and `rg "<<"`
  respectively.
* Deprecate MakeMatrix()

wpilibc/src/main/native/cpp/simulation/DifferentialDrivetrainSim.cpp

@@ -41,8 +41,8 @@ DifferentialDrivetrainSim::DifferentialDrivetrainSim(
               driveMotor, mass, wheelRadius, trackWidth / 2.0, J, gearing),
           trackWidth, driveMotor, gearing, wheelRadius, measurementStdDevs) {}
 
-Eigen::Matrix<double, 2, 1> DifferentialDrivetrainSim::ClampInput(
-    Eigen::Matrix<double, 2, 1> u) {
+Eigen::Vector<double, 2> DifferentialDrivetrainSim::ClampInput(
+    const Eigen::Vector<double, 2>& u) {
   return frc::NormalizeInputVector<2>(u,
                                       frc::RobotController::GetInputVoltage());
 }
@@ -66,11 +66,11 @@ double DifferentialDrivetrainSim::GetGearing() const {
   return m_currentGearing;
 }
 
-Eigen::Matrix<double, 7, 1> DifferentialDrivetrainSim::GetOutput() const {
+Eigen::Vector<double, 7> DifferentialDrivetrainSim::GetOutput() const {
   return m_y;
 }
 
-Eigen::Matrix<double, 7, 1> DifferentialDrivetrainSim::GetState() const {
+Eigen::Vector<double, 7> DifferentialDrivetrainSim::GetState() const {
   return m_x;
 }
 
@@ -117,7 +117,7 @@ units::ampere_t DifferentialDrivetrainSim::GetCurrentDraw() const {
 }
 
 void DifferentialDrivetrainSim::SetState(
-    const Eigen::Matrix<double, 7, 1>& state) {
+    const Eigen::Vector<double, 7>& state) {
   m_x = state;
 }
 
@@ -129,9 +129,8 @@ void DifferentialDrivetrainSim::SetPose(const frc::Pose2d& pose) {
   m_x(State::kRightPosition) = 0;
 }
 
-Eigen::Matrix<double, 7, 1> DifferentialDrivetrainSim::Dynamics(
-    const Eigen::Matrix<double, 7, 1>& x,
-    const Eigen::Matrix<double, 2, 1>& u) {
+Eigen::Vector<double, 7> DifferentialDrivetrainSim::Dynamics(
+    const Eigen::Vector<double, 7>& x, const Eigen::Vector<double, 2>& u) {
   // Because G^2 can be factored out of A, we can divide by the old ratio
   // squared and multiply by the new ratio squared to get a new drivetrain
   // model.
@@ -150,7 +149,7 @@ Eigen::Matrix<double, 7, 1> DifferentialDrivetrainSim::Dynamics(
 
   double v = (x(State::kLeftVelocity) + x(State::kRightVelocity)) / 2.0;
 
-  Eigen::Matrix<double, 7, 1> xdot;
+  Eigen::Vector<double, 7> xdot;
   xdot(0) = v * std::cos(x(State::kHeading));
   xdot(1) = v * std::sin(x(State::kHeading));
   xdot(2) =

wpilibc/src/main/native/cpp/simulation/ElevatorSim.cpp

@@ -6,7 +6,6 @@
 
 #include <wpi/MathExtras.h>
 
-#include "frc/StateSpaceUtil.h"
 #include "frc/system/NumericalIntegration.h"
 #include "frc/system/plant/LinearSystemId.h"
 
@@ -79,25 +78,25 @@ units::ampere_t ElevatorSim::GetCurrentDraw() const {
 }
 
 void ElevatorSim::SetInputVoltage(units::volt_t voltage) {
-  SetInput(frc::MakeMatrix<1, 1>(voltage.to<double>()));
+  SetInput(Eigen::Vector<double, 1>{voltage.to<double>()});
 }
 
-Eigen::Matrix<double, 2, 1> ElevatorSim::UpdateX(
-    const Eigen::Matrix<double, 2, 1>& currentXhat,
-    const Eigen::Matrix<double, 1, 1>& u, units::second_t dt) {
+Eigen::Vector<double, 2> ElevatorSim::UpdateX(
+    const Eigen::Vector<double, 2>& currentXhat,
+    const Eigen::Vector<double, 1>& u, units::second_t dt) {
   auto updatedXhat = RKDP(
-      [&](const Eigen::Matrix<double, 2, 1>& x,
-          const Eigen::Matrix<double, 1, 1>& u_)
-          -> Eigen::Matrix<double, 2, 1> {
-        return m_plant.A() * x + m_plant.B() * u_ + MakeMatrix<2, 1>(0.0, -9.8);
+      [&](const Eigen::Vector<double, 2>& x,
+          const Eigen::Vector<double, 1>& u_) -> Eigen::Vector<double, 2> {
+        return m_plant.A() * x + m_plant.B() * u_ +
+               Eigen::Vector<double, 2>{0.0, -9.8};
       },
       currentXhat, u, dt);
   // Check for collision after updating x-hat.
   if (WouldHitLowerLimit(units::meter_t(updatedXhat(0)))) {
-    return MakeMatrix<2, 1>(m_minHeight.to<double>(), 0.0);
+    return Eigen::Vector<double, 2>{m_minHeight.to<double>(), 0.0};
   }
   if (WouldHitUpperLimit(units::meter_t(updatedXhat(0)))) {
-    return MakeMatrix<2, 1>(m_maxHeight.to<double>(), 0.0);
+    return Eigen::Vector<double, 2>{m_maxHeight.to<double>(), 0.0};
   }
   return updatedXhat;
 }

wpilibc/src/main/native/cpp/simulation/FlywheelSim.cpp

@@ -38,5 +38,5 @@ units::ampere_t FlywheelSim::GetCurrentDraw() const {
 }
 
 void FlywheelSim::SetInputVoltage(units::volt_t voltage) {
-  SetInput(frc::MakeMatrix<1, 1>(voltage.to<double>()));
+  SetInput(Eigen::Vector<double, 1>{voltage.to<double>()});
 }

wpilibc/src/main/native/cpp/simulation/SingleJointedArmSim.cpp

@@ -72,12 +72,12 @@ units::ampere_t SingleJointedArmSim::GetCurrentDraw() const {
 }
 
 void SingleJointedArmSim::SetInputVoltage(units::volt_t voltage) {
-  SetInput(frc::MakeMatrix<1, 1>(voltage.to<double>()));
+  SetInput(Eigen::Vector<double, 1>{voltage.to<double>()});
 }
 
-Eigen::Matrix<double, 2, 1> SingleJointedArmSim::UpdateX(
-    const Eigen::Matrix<double, 2, 1>& currentXhat,
-    const Eigen::Matrix<double, 1, 1>& u, units::second_t dt) {
+Eigen::Vector<double, 2> SingleJointedArmSim::UpdateX(
+    const Eigen::Vector<double, 2>& currentXhat,
+    const Eigen::Vector<double, 1>& u, units::second_t dt) {
   // Horizontal case:
   // Torque = F * r = I * alpha
   // alpha = F * r / I
@@ -88,14 +88,15 @@ Eigen::Matrix<double, 2, 1> SingleJointedArmSim::UpdateX(
   // We therefore find that f(x, u) = Ax + Bu + [[0] [m * g * r / I *
   // std::cos(theta)]]
 
-  Eigen::Matrix<double, 2, 1> updatedXhat = RKDP(
-      [&](const auto& x, const auto& u) -> Eigen::Matrix<double, 2, 1> {
-        Eigen::Matrix<double, 2, 1> xdot = m_plant.A() * x + m_plant.B() * u;
+  Eigen::Vector<double, 2> updatedXhat = RKDP(
+      [&](const auto& x, const auto& u) -> Eigen::Vector<double, 2> {
+        Eigen::Vector<double, 2> xdot = m_plant.A() * x + m_plant.B() * u;
 
         if (m_simulateGravity) {
-          xdot += MakeMatrix<2, 1>(0.0, (m_mass * m_r * -9.8 * 3.0 /
-                                         (m_mass * m_r * m_r) * std::cos(x(0)))
-                                            .template to<double>());
+          xdot += Eigen::Vector<double, 2>{
+              0.0, (m_mass * m_r * -9.8 * 3.0 / (m_mass * m_r * m_r) *
+                    std::cos(x(0)))
+                       .template to<double>()};
         }
         return xdot;
       },
@@ -103,9 +104,9 @@ Eigen::Matrix<double, 2, 1> SingleJointedArmSim::UpdateX(
 
   // Check for collisions.
   if (WouldHitLowerLimit(units::radian_t(updatedXhat(0)))) {
-    return MakeMatrix<2, 1>(m_minAngle.to<double>(), 0.0);
+    return Eigen::Vector<double, 2>{m_minAngle.to<double>(), 0.0};
   } else if (WouldHitUpperLimit(units::radian_t(updatedXhat(0)))) {
-    return MakeMatrix<2, 1>(m_maxAngle.to<double>(), 0.0);
+    return Eigen::Vector<double, 2>{m_maxAngle.to<double>(), 0.0};
   }
   return updatedXhat;
 }