[wpimath] Add typedefs for common types

This makes complex code significantly easier to read.

frc::Vectord<Size> = Eigen::Vector<double, Size>
frc::Matrixd<Rows, Cols> = Eigen::Matrix<double, Rows, Cols>

wpilibc/src/main/native/include/frc/simulation/DifferentialDrivetrainSim.h

@@ -4,11 +4,11 @@
 
 #pragma once
 
+#include <frc/EigenCore.h>
 #include <frc/kinematics/DifferentialDriveKinematics.h>
 #include <frc/system/LinearSystem.h>
 #include <frc/system/plant/DCMotor.h>
 
-#include <Eigen/Core>
 #include <units/length.h>
 #include <units/moment_of_inertia.h>
 #include <units/time.h>
@@ -80,7 +80,7 @@ class DifferentialDrivetrainSim {
    * @param u The input vector.
    * @return The normalized input.
    */
-  Eigen::Vector<double, 2> ClampInput(const Eigen::Vector<double, 2>& u);
+  Vectord<2> ClampInput(const Vectord<2>& u);
 
   /**
    * Sets the applied voltage to the drivetrain. Note that positive voltage must
@@ -178,7 +178,7 @@ class DifferentialDrivetrainSim {
    *
    * @param state The state.
    */
-  void SetState(const Eigen::Vector<double, 7>& state);
+  void SetState(const Vectord<7>& state);
 
   /**
    * Sets the system pose.
@@ -187,8 +187,7 @@ class DifferentialDrivetrainSim {
    */
   void SetPose(const frc::Pose2d& pose);
 
-  Eigen::Vector<double, 7> Dynamics(const Eigen::Vector<double, 7>& x,
-                                    const Eigen::Vector<double, 2>& u);
+  Vectord<7> Dynamics(const Vectord<7>& x, const Vectord<2>& u);
 
   class State {
    public:
@@ -301,7 +300,7 @@ class DifferentialDrivetrainSim {
   /**
    * Returns the current output vector y.
    */
-  Eigen::Vector<double, 7> GetOutput() const;
+  Vectord<7> GetOutput() const;
 
   /**
    * Returns an element of the state vector. Note that this will not include
@@ -314,7 +313,7 @@ class DifferentialDrivetrainSim {
   /**
    * Returns the current state vector x. Note that this will not include noise!
    */
-  Eigen::Vector<double, 7> GetState() const;
+  Vectord<7> GetState() const;
 
   LinearSystem<2, 2, 2> m_plant;
   units::meter_t m_rb;
@@ -325,9 +324,9 @@ class DifferentialDrivetrainSim {
   double m_originalGearing;
   double m_currentGearing;
 
-  Eigen::Vector<double, 7> m_x;
-  Eigen::Vector<double, 2> m_u;
-  Eigen::Vector<double, 7> m_y;
+  Vectord<7> m_x;
+  Vectord<2> m_u;
+  Vectord<7> m_y;
   std::array<double, 7> m_measurementStdDevs;
 };
 }  // namespace frc::sim

wpilibc/src/main/native/include/frc/simulation/ElevatorSim.h

@@ -127,9 +127,8 @@ class ElevatorSim : public LinearSystemSim<2, 1, 1> {
    * @param u           The system inputs (voltage).
    * @param dt          The time difference between controller updates.
    */
-  Eigen::Vector<double, 2> UpdateX(const Eigen::Vector<double, 2>& currentXhat,
-                                   const Eigen::Vector<double, 1>& u,
-                                   units::second_t dt) override;
+  Vectord<2> UpdateX(const Vectord<2>& currentXhat, const Vectord<1>& u,
+                     units::second_t dt) override;
 
  private:
   DCMotor m_gearbox;

wpilibc/src/main/native/include/frc/simulation/LinearSystemSim.h

@@ -6,10 +6,10 @@
 
 #include <array>
 
-#include <Eigen/Core>
 #include <units/current.h>
 #include <units/time.h>
 
+#include "frc/EigenCore.h"
 #include "frc/RobotController.h"
 #include "frc/StateSpaceUtil.h"
 #include "frc/system/LinearSystem.h"
@@ -40,9 +40,9 @@ class LinearSystemSim {
       const LinearSystem<States, Inputs, Outputs>& system,
       const std::array<double, Outputs>& measurementStdDevs = {})
       : m_plant(system), m_measurementStdDevs(measurementStdDevs) {
-    m_x = Eigen::Vector<double, States>::Zero();
-    m_y = Eigen::Vector<double, Outputs>::Zero();
-    m_u = Eigen::Vector<double, Inputs>::Zero();
+    m_x = Vectord<States>::Zero();
+    m_y = Vectord<Outputs>::Zero();
+    m_u = Vectord<Inputs>::Zero();
   }
 
   virtual ~LinearSystemSim() = default;
@@ -71,7 +71,7 @@ class LinearSystemSim {
    *
    * @return The current output of the plant.
    */
-  const Eigen::Vector<double, Outputs>& GetOutput() const { return m_y; }
+  const Vectord<Outputs>& GetOutput() const { return m_y; }
 
   /**
    * Returns an element of the current output of the plant.
@@ -86,7 +86,7 @@ class LinearSystemSim {
    *
    * @param u The system inputs.
    */
-  void SetInput(const Eigen::Vector<double, Inputs>& u) { m_u = ClampInput(u); }
+  void SetInput(const Vectord<Inputs>& u) { m_u = ClampInput(u); }
 
   /*
    * Sets the system inputs.
@@ -104,7 +104,7 @@ class LinearSystemSim {
    *
    * @param state The new state.
    */
-  void SetState(const Eigen::Vector<double, States>& state) { m_x = state; }
+  void SetState(const Vectord<States>& state) { m_x = state; }
 
   /**
    * Returns the current drawn by this simulated system. Override this method to
@@ -124,9 +124,9 @@ class LinearSystemSim {
    * @param u           The system inputs (usually voltage).
    * @param dt          The time difference between controller updates.
    */
-  virtual Eigen::Vector<double, States> UpdateX(
-      const Eigen::Vector<double, States>& currentXhat,
-      const Eigen::Vector<double, Inputs>& u, units::second_t dt) {
+  virtual Vectord<States> UpdateX(const Vectord<States>& currentXhat,
+                                  const Vectord<Inputs>& u,
+                                  units::second_t dt) {
     return m_plant.CalculateX(currentXhat, u, dt);
   }
 
@@ -137,16 +137,16 @@ class LinearSystemSim {
    * @param u          The input vector.
    * @return The normalized input.
    */
-  Eigen::Vector<double, Inputs> ClampInput(Eigen::Vector<double, Inputs> u) {
+  Vectord<Inputs> ClampInput(Vectord<Inputs> u) {
     return frc::DesaturateInputVector<Inputs>(
         u, frc::RobotController::GetInputVoltage());
   }
 
   LinearSystem<States, Inputs, Outputs> m_plant;
 
-  Eigen::Vector<double, States> m_x;
-  Eigen::Vector<double, Outputs> m_y;
-  Eigen::Vector<double, Inputs> m_u;
+  Vectord<States> m_x;
+  Vectord<Outputs> m_y;
+  Vectord<Inputs> m_u;
   std::array<double, Outputs> m_measurementStdDevs;
 };
 }  // namespace frc::sim

wpilibc/src/main/native/include/frc/simulation/SingleJointedArmSim.h

@@ -142,9 +142,8 @@ class SingleJointedArmSim : public LinearSystemSim<2, 1, 1> {
    * @param u           The system inputs (voltage).
    * @param dt          The time difference between controller updates.
    */
-  Eigen::Vector<double, 2> UpdateX(const Eigen::Vector<double, 2>& currentXhat,
-                                   const Eigen::Vector<double, 1>& u,
-                                   units::second_t dt) override;
+  Vectord<2> UpdateX(const Vectord<2>& currentXhat, const Vectord<1>& u,
+                     units::second_t dt) override;
 
  private:
   units::meter_t m_r;