Replace hardcoded values for Pi (#20235)

* Avoid redefining pi, use instead math.pi or M_PI from math.h

* Revert overwriting of the gpsPi variable, which is part the GPS standard.

* Move standard library imports to top, remove standard library import comments.
old-commit-hash: 93911a7dbe

selfdrive/car/ford/carcontroller.py

@@ -1,3 +1,4 @@
+import math
 from cereal import car
 from selfdrive.car import make_can_msg
 from selfdrive.car.ford.fordcan import create_steer_command, create_lkas_ui, spam_cancel_button
@@ -33,7 +34,7 @@ class CarController():
 
       if (frame % 3) == 0:
 
-        curvature = self.vehicle_model.calc_curvature(actuators.steeringAngleDeg*3.1415/180., CS.out.vEgo)
+        curvature = self.vehicle_model.calc_curvature(actuators.steeringAngleDeg*math.pi/180., CS.out.vEgo)
 
         # The use of the toggle below is handy for trying out the various LKAS modes
         if TOGGLE_DEBUG:

selfdrive/car/mock/interface.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+import math
 from cereal import car
 from selfdrive.config import Conversions as CV
 from selfdrive.swaglog import cloudlog
@@ -10,7 +11,7 @@ from selfdrive.car.interfaces import CarInterfaceBase
 TS = 0.01  # 100Hz
 YAW_FR = 0.2  # ~0.8s time constant on yaw rate filter
 # low pass gain
-LPG = 2 * 3.1415 * YAW_FR * TS / (1 + 2 * 3.1415 * YAW_FR * TS)
+LPG = 2 * math.pi * YAW_FR * TS / (1 + 2 * math.pi * YAW_FR * TS)
 
 
 class CarInterface(CarInterfaceBase):

selfdrive/controls/lib/lateral_mpc/generator.cpp

@@ -1,8 +1,8 @@
+#include <math.h>
 #include <acado_code_generation.hpp>
 #include "common/modeldata.h"
 
-#define PI 3.1415926536
-#define deg2rad(d) (d/180.0*PI)
+#define deg2rad(d) (d/180.0*M_PI)
 
 const int N_steps = 16;
 using namespace std;
@@ -23,7 +23,7 @@ int main( )
   OnlineData rotation_radius;
 
   Control curvature_rate;
-  
+
 
   // Equations of motion
   f << dot(xx) == v_ego * cos(psi) - rotation_radius * sin(psi) * (v_ego * curvature);