$Id: History,v 1.27 2000/05/31 15:51:46 gcosmo Exp $
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     =========================================================
     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                      Category History file
                      ---------------------
This file should be used by G4 developers and category coordinators
to briefly summarize all major modifications introduced in the code
and keep track of all category-tags.
It DOES NOT substitute the  CVS log-message one should put at every
committal in the CVS repository !

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     * Reverse chronological order (last date on top), please *
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May     17th, 2000   G. Cosmo - geomvol-V01-01-01

G4ReplicaNavigation.cc:
- Added check to returned safety value in DistanceToOut(). Zero is
  returned if the computed velue is less than kCarTolerance.
- Introduced temporary fix to ComputeStep() in the first step computation
  for replica boundaries. 'ourStep' is not set to the computed 'sampleStep'
  if 'sampleStep' happens to be zero.
  This fix helps to get rid of infinite loops when a point is on a
  shared surface of a replica or on a shared vertex; a more definitive
  solution to the problem is needed for the correct replica location.

May     16th, 2000   J. Apostolakis

G4PropagatorInField[.hh.icc]:
- Added implementations for SetDeltaOneStep and SetDeltaIntersection.

May      9th, 2000   J. Apostolakis - geomvol-V01-01-00

Improvements in G4PropagatorInField  incorporating include file fixes
in geometry-V01-01-02
[ ie: Introduced kCarTolerance for check over taken step length and
TruePathLength in G4PropagatorInField::ComputeStep(). ]


May      8th, 2000   J. Apostolakis - geomvol-fieldImprove1

Internal tag for version that improves the behavior of the field.
[ it does not include the changes of geometry-V01-01-02 ] 

May      5th, 2000   J. Apostolakis 

G4PropagatorInField improvements modifying:
 i) the comparison for detecting probable loop condition
      - to accomodate solids that (wrongly) return small finite answer instead
        of zero for Distance on surface.  [ can probably be reversed eventually]
ii) the condition for exit from while (sufficient path length) to
    avoid making a very small final step :  used the tolerance.

April 25th, 2000   G. Cosmo

- Reorganised comments for the Software Reference Manual.
- Moved inlined definition to .icc files, where needed.
  Created: G4LogicalBorderSurface.icc and G4LogicalSkinSurface.icc.
- Removed obsolete G4Transform class. Removed files:
  G4Transform[.hh.icc].

January 19th, 2000   G. Cosmo - geomvol-V01-00-00

Sycronized files versions with HEAD after ISO-C++ migration.
(essentially CVS headers changes). Left out only G4Navigator[.hh.cc].

December 2nd, 1999   G. Cosmo - geomvol-V00-01-02

G4TransportationManager: Fixed definition of the singleton to conform
    to the canonical implementation. Moved default constructor from private
    to protected and added call to G4Exception in case of multiple instances
    through derived classes.

November 26th, 1999   J. Apostolakis - geomvol-V00-01-01

G4TouchableHistory: Moved GetTranslation and GetRotation from inline file 
    to source file -- as they use static variables in the methods themselves.
        --> cannot be handled by new HP aCC compiler

G4PropagatorInField: Initialised fVerboseLevel in constructor. (omision)
        --> on WinNT 4.0sp4 / VC++ 6.0  it was given value of 1 not 0.

November 10th, 1999   J. Apostolakis - geomvol-01-01-01b

Modified test/GNUmakefile to make it use fully-granular libraries.
New test code in testG4Volumes for Object/Frame Rotation/Translation.

October  29th, 1999   J. Apostolakis - geomvol-01-01-01a

Moved initialisation of static data members of G4PropagatorInField 
  fDefault_Delta_Intersection_Val
  fDefault_Delta_One_Step_Value 
to G4TransportationManager.cc, to ensure correct order initialisation 
of static (class) data members 

G4PropagatorInField warning message about integration inaccuracy 
now printed (for a maximum of 10 times) and in Verbose. 

July     27th, 1999   J. Apostolakis - geomvol-01-01-02

Modified G4Navigator to distinguish Candidate volume from Blocked volume

July     27th, 1999   J. Apostolakis - geomvol-01-01-01

Tagged  --- here ??? ---

July     27th, 1999   J. Apostolakis
G4PropagatorInField:
Added instance variables to keep track of "abnormal" case - which caused loop:

  This is induced when a step at a boundary goes into one volume
    - but in that volume it encounters an intermediate boundary
      and when the step is subdivided it finds a zero step.
   Then it looped between the volumes

This is corrected by finding this problem (#subsequent zero steps > threshold)
and attempting ever smaller trial steps until it succeeds.

->  it was not done for the first step

July     27th, 1999   J. Apostolakis

G4PropagatorInField:
  Made DeltaIntersection and DeltaOneStep instance variables (not class var.)
  Added Get/Set methods.   Old  values of are now the defaults.


July      1st, 1999   J. Apostolakis - field-01-00-06a

In G4PropagatorInField   --> method LocateIntersectionPoint():

  Integration inaccuracies cause an internal step's mid-point and endpoint
    to be further apart than their curve length difference.  (Unphysical)

  In order to compensate, we re-compute the step's endpoint.  [ This also
    requires modification in G4ChordFinder::ApproxCurvePointV  ]

A better solution would be to re-start/re-structure the loop to handle this
sort of case.   But this would be a more major change ...

May      19, 99      J.Apostolakis, F. Behner

   In G4Navigator: Changed cout -> G4cout
		   Changed protection for printing of Physical volume name:
		    (because of warning on SUN;  same functionality)


   In G4NavigationLevel, created an optional operator delete(void *, void *)
    this is accepted by DEC, and not accepted by SUN, HP
    new flag created in architecture for protection: ~ G4NO_ISO_DELETES 

May      17, 99      J. Allison.
   In G4NavigationLevel, changed operator new(size_t, G4NavigationLevel *)
   to operator new(size_t, void *) because the former is not accepted
   by Sun CC 4.2 (with STL Interface.)

May       3, 99      J. Apostolakis 
   testG4ReplicaNavigation.cc
      Changed comparison of doubles, to give it a tolerance.  

April     8, 99      (committed & recorded J. Apostolakis  May 3rd)
   G4NavigationLevel.{hh,icc}: Minor Changes 
      added const to copy constructor and
      new 'new' operator with size_t - for STL use with preallocated containers" 


March    19, 99      J. Apostolakis        geomvol-01-00-03

   New tag for replica fix.


March    18, 99      J. Apostolakis

   A fix for looping in Replicas:
        In the case where a zero step is done in Replicas, we must allow
    ReplicaNavigator to handle the case itself - or else we loop.

March    11, 99      J. Apostolakis

   G4GRSVolume.icc: corrected G4Exception messages.

February 18, 99      J. Apostolakis        

 include/G4VoxelNavigation.hh
 src/G4VoxelNavigation.cc    : overwrote versions 1.2 with production version
      --->  when changes are refined and retested, they could be reincorporated

February 17, 99      J. Apostolakis        geomvol-01-00-02

 Moved G4PropagatorInField here from magneticfield to remove correct
  dependency.

February 15, 99      J. Apostolakis        geomvol-01-00-01

   Only fixes in G4Navigator's incorporated.
   GNUmakefile corrected (for SUN-CC).

January      99,     J. Apostolakis

Fix for ComputeSafety in Navigator:                              G4Navigator.cc
            the voxel information that was used was incorrect       v 1.3
                -> it resulted in wrong value of safety


December     98                                   geant4-00-RandD

 include/G4VoxelNavigation.hh
 src/G4VoxelNavigation.cc    : versions 1.2 are trial versions from beta "head"

December     98                                   

Trial fix for navigation in replicas                             G4Navigator.cc
                                                                    v 1.2
         (a problem persists with this version)


December     98                                   geant4-00

   Code moved: production tag from beta repository.
