src/FDM/JSBSim/models/FGPropagate.cpp

   1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2
   3  Module:       FGPropagate.cpp
   4  Author:       Jon S. Berndt
   5  Date started: 01/05/99
   6  Purpose:      Integrate the EOM to determine instantaneous position
   7  Called by:    FGFDMExec
   8
   9  ------------- Copyright (C) 1999  Jon S. Berndt (jsb@hal-pc.org) -------------
  10
  11  This program is free software; you can redistribute it and/or modify it under
  12  the terms of the GNU Lesser General Public License as published by the Free Software
  13  Foundation; either version 2 of the License, or (at your option) any later
  14  version.
  15
  16  This program is distributed in the hope that it will be useful, but WITHOUT
  17  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  18  FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
  19  details.
  20
  21  You should have received a copy of the GNU Lesser General Public License along with
  22  this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  23  Place - Suite 330, Boston, MA  02111-1307, USA.
  24
  25  Further information about the GNU Lesser General Public License can also be found on
  26  the world wide web at http://www.gnu.org.
  27
  28 FUNCTIONAL DESCRIPTION
  29 --------------------------------------------------------------------------------
  30 This class encapsulates the integration of rates and accelerations to get the
  31 current position of the aircraft.
  32
  33 HISTORY
  34 --------------------------------------------------------------------------------
  35 01/05/99   JSB   Created
  36
  37 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  38 COMMENTS, REFERENCES,  and NOTES
  39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  40 [1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling
  41     Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420  Naval Postgraduate
  42     School, January 1994
  43 [2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices",
  44     JSC 12960, July 1977
  45 [3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at
  46     NASA-Ames", NASA CR-2497, January 1975
  47 [4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
  48     Wiley & Sons, 1979 ISBN 0-471-03032-5
  49 [5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons,
  50     1982 ISBN 0-471-08936-2
  51
  52 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  53 INCLUDES
  54 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  55
  56 #ifdef FGFS
  57 #  include <simgear/compiler.h>
  58 #  ifdef SG_HAVE_STD_INCLUDES
  59 #    include <cmath>
  60 #    include <iomanip>
  61 #  else
  62 #    include <math.h>
  63 #    include <iomanip.h>
  64 #  endif
  65 #else
  66 #  if defined(sgi) && !defined(__GNUC__)
  67 #    include <math.h>
  68 #    if (_COMPILER_VERSION < 740)
  69 #      include <iomanip.h>
  70 #    else
  71 #      include <iomanip>
  72 #    endif
  73 #  else
  74 #    include <cmath>
  75 #    include <iomanip>
  76 #  endif
  77 #endif
  78
  79 #include "FGPropagate.h"
  80 #include <FGState.h>
  81 #include <FGFDMExec.h>
  82 #include "FGAircraft.h"
  83 #include "FGMassBalance.h"
  84 #include "FGInertial.h"
  85 #include <input_output/FGPropertyManager.h>
  86
  87 namespace JSBSim {
  88
  89 static const char *IdSrc = "$Id$";
  90 static const char *IdHdr = ID_PROPAGATE;
  91
  92 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  93 CLASS IMPLEMENTATION
  94 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  95
  96 FGPropagate::FGPropagate(FGFDMExec* fdmex) : FGModel(fdmex)
  97 {
  98   Name = "FGPropagate";
  99 //  vQtrndot.zero();
 100
 101   bind();
 102   Debug(0);
 103 }
 104
 105 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 106
 107 FGPropagate::~FGPropagate(void)
 108 {
 109   unbind();
 110   Debug(1);
 111 }
 112
 113 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 114
 115 bool FGPropagate::InitModel(void)
 116 {
 117   FGModel::InitModel();
 118
 119   SeaLevelRadius = Inertial->RefRadius();          // For initialization ONLY
 120   RunwayRadius   = SeaLevelRadius;
 121
 122   VState.vLocation.SetRadius( SeaLevelRadius + 4.0 );
 123
 124   return true;
 125 }
 126
 127 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 128
 129 void FGPropagate::SetInitialState(const FGInitialCondition *FGIC)
 130 {
 131   SeaLevelRadius = FGIC->GetSeaLevelRadiusFtIC();
 132   RunwayRadius = SeaLevelRadius;
 133
 134   // Set the position lat/lon/radius
 135   VState.vLocation = FGLocation( FGIC->GetLongitudeRadIC(),
 136                           FGIC->GetLatitudeRadIC(),
 137                           FGIC->GetAltitudeFtIC() + FGIC->GetSeaLevelRadiusFtIC() );
 138
 139   // Set the Orientation from the euler angles
 140   VState.vQtrn = FGQuaternion( FGIC->GetPhiRadIC(),
 141                         FGIC->GetThetaRadIC(),
 142                         FGIC->GetPsiRadIC() );
 143
 144   // Set the velocities in the instantaneus body frame
 145   VState.vUVW = FGColumnVector3( FGIC->GetUBodyFpsIC(),
 146                           FGIC->GetVBodyFpsIC(),
 147                           FGIC->GetWBodyFpsIC() );
 148
 149   // Set the angular velocities in the instantaneus body frame.
 150   VState.vPQR = FGColumnVector3( FGIC->GetPRadpsIC(),
 151                           FGIC->GetQRadpsIC(),
 152                           FGIC->GetRRadpsIC() );
 153
 154   // Compute some derived values.
 155   vVel = VState.vQtrn.GetTInv()*VState.vUVW;
 156
 157   // Finally, make sure that the quaternion stays normalized.
 158   VState.vQtrn.Normalize();
 159
 160   // Recompute the RunwayRadius level.
 161   RecomputeRunwayRadius();
 162 }
 163
 164 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 165 /*
 166 Purpose: Called on a schedule to perform EOM integration
 167 Notes:   [JB] Run in standalone mode, SeaLevelRadius will be reference radius.
 168          In FGFS, SeaLevelRadius is stuffed from FGJSBSim in JSBSim.cxx each pass.
 169
 170 At the top of this Run() function, see several "shortcuts" (or, aliases) being
 171 set up for use later, rather than using the longer class->function() notation.
 172
 173 Here, propagation of state is done using a simple explicit Euler scheme (see the
 174 bottom of the function). This propagation is done using the current state values
 175 and current derivatives. Based on these values we compute an approximation to the
 176 state values for (now + dt).
 177
 178 */
 179
 180 bool FGPropagate::Run(void)
 181 {
 182   if (FGModel::Run()) return true;  // Fast return if we have nothing to do ...
 183   if (FDMExec->Holding()) return false;
 184
 185   RecomputeRunwayRadius();
 186
 187   double dt = State->Getdt()*rate;  // The 'stepsize'
 188   const FGColumnVector3 omega( 0.0, 0.0, Inertial->omega() ); // earth rotation
 189   const FGColumnVector3& vForces = Aircraft->GetForces();     // current forces
 190   const FGColumnVector3& vMoments = Aircraft->GetMoments();   // current moments
 191
 192   double mass = MassBalance->GetMass();             // mass
 193   const FGMatrix33& J = MassBalance->GetJ();        // inertia matrix
 194   const FGMatrix33& Jinv = MassBalance->GetJinv();  // inertia matrix inverse
 195   double r = GetRadius();                           // radius
 196   if (r == 0.0) {cerr << "radius = 0 !" << endl; r = 1e-16;} // radius check
 197   double rInv = 1.0/r;
 198   FGColumnVector3 gAccel( 0.0, 0.0, Inertial->GetGAccel(r) );
 199
 200   // The rotation matrices:
 201   const FGMatrix33& Tl2b = GetTl2b();  // local to body frame
 202   const FGMatrix33& Tb2l = GetTb2l();  // body to local frame
 203   const FGMatrix33& Tec2l = VState.vLocation.GetTec2l();  // earth centered to local frame
 204   const FGMatrix33& Tl2ec = VState.vLocation.GetTl2ec();  // local to earth centered frame
 205
 206   // Inertial angular velocity measured in the body frame.
 207   const FGColumnVector3 pqri = VState.vPQR + Tl2b*(Tec2l*omega);
 208
 209   // Compute vehicle velocity wrt EC frame, expressed in Local horizontal frame.
 210   vVel = Tb2l * VState.vUVW;
 211
 212   // First compute the time derivatives of the vehicle state values:
 213
 214   // Compute body frame rotational accelerations based on the current body moments
 215   vPQRdot = Jinv*(vMoments - pqri*(J*pqri));
 216
 217   // Compute body frame accelerations based on the current body forces
 218   vUVWdot = VState.vUVW*VState.vPQR + vForces/mass;
 219
 220   // Coriolis acceleration.
 221   FGColumnVector3 ecVel = Tl2ec*vVel;
 222   FGColumnVector3 ace = 2.0*omega*ecVel;
 223   vUVWdot -= Tl2b*(Tec2l*ace);
 224
 225   if (!GroundReactions->GetWOW()) {
 226     // Centrifugal acceleration.
 227     FGColumnVector3 aeec = omega*(omega*VState.vLocation);
 228     vUVWdot -= Tl2b*(Tec2l*aeec);
 229   }
 230
 231   // Gravitation accel
 232   vUVWdot += Tl2b*gAccel;
 233
 234   // Compute vehicle velocity wrt EC frame, expressed in EC frame
 235   vLocationDot = Tl2ec * vVel;
 236
 237   FGColumnVector3 omegaLocal( rInv*vVel(eEast),
 238                               -rInv*vVel(eNorth),
 239                               -rInv*vVel(eEast)*VState.vLocation.GetTanLatitude() );
 240
 241   // Compute quaternion orientation derivative on current body rates
 242   vQtrndot = VState.vQtrn.GetQDot( VState.vPQR - Tl2b*omegaLocal );
 243
 244   // Integrate to propagate the state
 245
 246   // Propagate rotational velocity
 247
 248   // VState.vPQR += dt*(1.5*vPQRdot - 0.5*last_vPQRdot); // Adams-Bashforth
 249   VState.vPQR += (1/12.0)*dt*(23.0*vPQRdot - 16.0*last_vPQRdot + 5.0*last2_vPQRdot); // Adams-Bashforth 3
 250   // VState.vPQR += dt*vPQRdot;                          // Rectangular Euler
 251   // VState.vPQR += 0.5*dt*(vPQRdot + last_vPQRdot);     // Trapezoidal
 252
 253   // Propagate translational velocity
 254
 255   // VState.vUVW += dt*(1.5*vUVWdot - 0.5*last_vUVWdot); // Adams Bashforth
 256   VState.vUVW += (1/12.0)*dt*(23.0*vUVWdot - 16.0*last_vUVWdot + 5.0*last2_vUVWdot); // Adams-Bashforth 3
 257   // VState.vUVW += dt*vUVWdot;                         // Rectangular Euler
 258   // VState.vUVW += 0.5*dt*(vUVWdot + last_vUVWdot);    // Trapezoidal
 259
 260   // Propagate angular position
 261
 262   // VState.vQtrn += dt*(1.5*vQtrndot - 0.5*last_vQtrndot); // Adams Bashforth
 263   VState.vQtrn += (1/12.0)*dt*(23.0*vQtrndot - 16.0*last_vQtrndot + 5.0*last2_vQtrndot); // Adams-Bashforth 3
 264   // VState.vQtrn += dt*vQtrndot;                           // Rectangular Euler
 265   // VState.vQtrn += 0.5*dt*(vQtrndot + last_vQtrndot);     // Trapezoidal
 266
 267   // Propagate translational position
 268
 269   // VState.vLocation += dt*(1.5*vLocationDot - 0.5*last_vLocationDot); // Adams Bashforth
 270   VState.vLocation += (1/12.0)*dt*(23.0*vLocationDot - 16.0*last_vLocationDot + 5.0*last2_vLocationDot); // Adams-Bashforth 3
 271   // VState.vLocation += dt*vLocationDot;                               // Rectangular Euler
 272   // VState.vLocation += 0.5*dt*(vLocationDot + last_vLocationDot);     // Trapezoidal
 273
 274   // Set past values
 275
 276   last2_vPQRdot = last_vPQRdot;
 277   last_vPQRdot = vPQRdot;
 278
 279   last2_vUVWdot = last_vUVWdot;
 280   last_vUVWdot = vUVWdot;
 281
 282   last2_vQtrndot = last_vQtrndot;
 283   last_vQtrndot = vQtrndot;
 284
 285   last2_vLocationDot = last_vLocationDot;
 286   last_vLocationDot = vLocationDot;
 287
 288   return false;
 289 }
 290
 291 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 292
 293 void FGPropagate::RecomputeRunwayRadius(void)
 294 {
 295   // Get the runway radius.
 296   FGLocation contactloc;
 297   FGColumnVector3 dv;
 298   FGGroundCallback* gcb = FDMExec->GetGroundCallback();
 299   double t = State->Getsim_time();
 300   gcb->GetAGLevel(t, VState.vLocation, contactloc, dv, dv);
 301   RunwayRadius = contactloc.GetRadius();
 302 }
 303
 304 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 305
 306 void FGPropagate::Seth(double tt)
 307 {
 308   VState.vLocation.SetRadius( tt + SeaLevelRadius );
 309 }
 310
 311 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 312
 313 double FGPropagate::GetRunwayRadius(void) const
 314 {
 315   return RunwayRadius;
 316 }
 317
 318 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 319
 320 double FGPropagate::GetDistanceAGL(void) const
 321 {
 322   return VState.vLocation.GetRadius() - RunwayRadius;
 323 }
 324
 325 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 326
 327 void FGPropagate::SetDistanceAGL(double tt)
 328 {
 329   VState.vLocation.SetRadius( tt + RunwayRadius );
 330 }
 331
 332 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 333
 334 void FGPropagate::bind(void)
 335 {
 336   typedef double (FGPropagate::*PMF)(int) const;
 337   PropertyManager->Tie("velocities/h-dot-fps", this, &FGPropagate::Gethdot);
 338
 339   PropertyManager->Tie("velocities/v-north-fps", this, eNorth, (PMF)&FGPropagate::GetVel);
 340   PropertyManager->Tie("velocities/v-east-fps", this, eEast, (PMF)&FGPropagate::GetVel);
 341   PropertyManager->Tie("velocities/v-down-fps", this, eDown, (PMF)&FGPropagate::GetVel);
 342
 343   PropertyManager->Tie("velocities/u-fps", this, eU, (PMF)&FGPropagate::GetUVW);
 344   PropertyManager->Tie("velocities/v-fps", this, eV, (PMF)&FGPropagate::GetUVW);
 345   PropertyManager->Tie("velocities/w-fps", this, eW, (PMF)&FGPropagate::GetUVW);
 346
 347   PropertyManager->Tie("velocities/p-rad_sec", this, eP, (PMF)&FGPropagate::GetPQR);
 348   PropertyManager->Tie("velocities/q-rad_sec", this, eQ, (PMF)&FGPropagate::GetPQR);
 349   PropertyManager->Tie("velocities/r-rad_sec", this, eR, (PMF)&FGPropagate::GetPQR);
 350
 351   PropertyManager->Tie("accelerations/pdot-rad_sec", this, eP, (PMF)&FGPropagate::GetPQRdot);
 352   PropertyManager->Tie("accelerations/qdot-rad_sec", this, eQ, (PMF)&FGPropagate::GetPQRdot);
 353   PropertyManager->Tie("accelerations/rdot-rad_sec", this, eR, (PMF)&FGPropagate::GetPQRdot);
 354
 355   PropertyManager->Tie("accelerations/udot-fps", this, eU, (PMF)&FGPropagate::GetUVWdot);
 356   PropertyManager->Tie("accelerations/vdot-fps", this, eV, (PMF)&FGPropagate::GetUVWdot);
 357   PropertyManager->Tie("accelerations/wdot-fps", this, eW, (PMF)&FGPropagate::GetUVWdot);
 358
 359   PropertyManager->Tie("position/h-sl-ft", this, &FGPropagate::Geth, &FGPropagate::Seth, true);
 360   PropertyManager->Tie("position/lat-gc-rad", this, &FGPropagate::GetLatitude, &FGPropagate::SetLatitude);
 361   PropertyManager->Tie("position/long-gc-rad", this, &FGPropagate::GetLongitude, &FGPropagate::SetLongitude);
 362   PropertyManager->Tie("position/h-agl-ft", this,  &FGPropagate::GetDistanceAGL, &FGPropagate::SetDistanceAGL);
 363   PropertyManager->Tie("position/radius-to-vehicle-ft", this, &FGPropagate::GetRadius);
 364
 365   PropertyManager->Tie("metrics/runway-radius", this, &FGPropagate::GetRunwayRadius);
 366
 367   PropertyManager->Tie("attitude/phi-rad", this, (int)ePhi, (PMF)&FGPropagate::GetEuler);
 368   PropertyManager->Tie("attitude/theta-rad", this, (int)eTht, (PMF)&FGPropagate::GetEuler);
 369   PropertyManager->Tie("attitude/psi-rad", this, (int)ePsi, (PMF)&FGPropagate::GetEuler);
 370
 371   PropertyManager->Tie("attitude/roll-rad", this, (int)ePhi, (PMF)&FGPropagate::GetEuler);
 372   PropertyManager->Tie("attitude/pitch-rad", this, (int)eTht, (PMF)&FGPropagate::GetEuler);
 373   PropertyManager->Tie("attitude/heading-true-rad", this, (int)ePsi, (PMF)&FGPropagate::GetEuler);
 374 }
 375
 376 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 377
 378 void FGPropagate::unbind(void)
 379 {
 380   PropertyManager->Untie("velocities/v-north-fps");
 381   PropertyManager->Untie("velocities/v-east-fps");
 382   PropertyManager->Untie("velocities/v-down-fps");
 383   PropertyManager->Untie("velocities/h-dot-fps");
 384   PropertyManager->Untie("velocities/u-fps");
 385   PropertyManager->Untie("velocities/v-fps");
 386   PropertyManager->Untie("velocities/w-fps");
 387   PropertyManager->Untie("velocities/p-rad_sec");
 388   PropertyManager->Untie("velocities/q-rad_sec");
 389   PropertyManager->Untie("velocities/r-rad_sec");
 390   PropertyManager->Untie("accelerations/udot-fps");
 391   PropertyManager->Untie("accelerations/vdot-fps");
 392   PropertyManager->Untie("accelerations/wdot-fps");
 393   PropertyManager->Untie("accelerations/pdot-rad_sec");
 394   PropertyManager->Untie("accelerations/qdot-rad_sec");
 395   PropertyManager->Untie("accelerations/rdot-rad_sec");
 396   PropertyManager->Untie("position/h-sl-ft");
 397   PropertyManager->Untie("position/lat-gc-rad");
 398   PropertyManager->Untie("position/long-gc-rad");
 399   PropertyManager->Untie("position/h-agl-ft");
 400   PropertyManager->Untie("position/radius-to-vehicle-ft");
 401   PropertyManager->Untie("metrics/runway-radius");
 402   PropertyManager->Untie("attitude/phi-rad");
 403   PropertyManager->Untie("attitude/theta-rad");
 404   PropertyManager->Untie("attitude/psi-rad");
 405   PropertyManager->Untie("attitude/roll-rad");
 406   PropertyManager->Untie("attitude/pitch-rad");
 407   PropertyManager->Untie("attitude/heading-true-rad");
 408 }
 409
 410 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 411 //    The bitmasked value choices are as follows:
 412 //    unset: In this case (the default) JSBSim would only print
 413 //       out the normally expected messages, essentially echoing
 414 //       the config files as they are read. If the environment
 415 //       variable is not set, debug_lvl is set to 1 internally
 416 //    0: This requests JSBSim not to output any messages
 417 //       whatsoever.
 418 //    1: This value explicity requests the normal JSBSim
 419 //       startup messages
 420 //    2: This value asks for a message to be printed out when
 421 //       a class is instantiated
 422 //    4: When this value is set, a message is displayed when a
 423 //       FGModel object executes its Run() method
 424 //    8: When this value is set, various runtime state variables
 425 //       are printed out periodically
 426 //    16: When set various parameters are sanity checked and
 427 //       a message is printed out when they go out of bounds
 428
 429 void FGPropagate::Debug(int from)
 430 {
 431   if (debug_lvl <= 0) return;
 432
 433   if (debug_lvl & 1) { // Standard console startup message output
 434     if (from == 0) { // Constructor
 435
 436     }
 437   }
 438   if (debug_lvl & 2 ) { // Instantiation/Destruction notification
 439     if (from == 0) cout << "Instantiated: FGPropagate" << endl;
 440     if (from == 1) cout << "Destroyed:    FGPropagate" << endl;
 441   }
 442   if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
 443   }
 444   if (debug_lvl & 8 ) { // Runtime state variables
 445   }
 446   if (debug_lvl & 16) { // Sanity checking
 447   }
 448   if (debug_lvl & 64) {
 449     if (from == 0) { // Constructor
 450       cout << IdSrc << endl;
 451       cout << IdHdr << endl;
 452     }
 453   }
 454 }
 455 }