File: CHANGELOG

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felt 3.02-4
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** Changes to FElt from 3.00 or 3.01 to 3.02 

The following changes were made to the FElt syntax:
   1. hooks for a gravity vector in the analysis section.  Doesn't
      do anything yet, but the syntax is there ...
   2. "static-substitution" and "static-incremental" are now valid 
      analysis types
   3. a "load cases" section and accompanying syntax for named
      load cases
   4. syntax for new analysis parameters, "tolerance", "iterations",
      "relaxation", "load-steps".
   5. input-node= and input-dof= parameters in the analysis 
      parameters to allow for parametric studies in which you
      get a table (or plot) of output that explores displacements
      as a function of force level at a single input point
   6. axial and radial are now valid directions for distributed loads

The following bugs/things were fixed/changed:
   1. the transform matrix for beam3d elements was incorrect if elements
      had nodes which were out of the x-y plane.
   2. several problems with the new Makefile scheme were corrected.
   3. velvet was probably getting the aspect ratios wrong in drawing 
      3d structures due to an error in the min/max checking.
   4. the spectrum components of force structures were not being
      initialized to either zero or NULL
   5. save's in velvet were actually doing dumps (save all's), minor, 
      but potentially annoying.
   6. there was still a problem with the lumped mass matrices for 
      htk elements.
   7. the new PrintGlobalMatrices routine took a file pointer but
      didn't actually use it; things were just going to stdout.
   8. internal error in burlap's interface wit the matrix lib
      was causing some problems with inversion and overwriting.
   9. there were problems with iso_2d elements (or any element with
      optional nodes) as the renumbering routines were just blindly
      looping through element -> definition -> numnodes rather than
      checking to make sure that all of the nodes were in fact valid.
  10. on a similar note, the checks in velvet for out-of-plane nodes
      were going over element -> definition -> numnodes rather than
      element -> definition -> shapenodes (which all have to be valid
      in the first place).
  11. there was some sort of problem with the pre-processor and
      corduroy (don't ask me how these things happen).  I think it's
      fixed now, but then again, I don't really know what was wrong.
  12. renamed AssembleStiffness and AssembleDynamic to ConstructStiffness
      and ConstructDynamic to reflect that they both create and assemble
      the matrices (this then parallels ConstructForceVector).  Renamed
      ConstructTransientForce to AssembleTransientForce to reflect 
      the fact it only fills the thing rather than creating it then
      filling it.
  13. the cpp command line wasn't being built properly so you couldn't
      actually use -I, -D and -U on the felt (and corduroy) command line
  14. memory initialization problem in Drawing.c
  15. 2d and 3d Athena widget specific defaults were moved into
      velvet.c and are now applied automatically at runtime as
      appropriate.
  16. the filename printing and scrolling in velvet's file dialog
      was improved.
  17. changed the analysis.nodes array into an array of actual node
      pointers rather than node numbers.  In some ways this adds
      a layer of complexity because whenever we input analysis nodes
      we have to resolve their numbers by doing tree lookups in the
      node tree; on the other hand, it is much more consistent with
      the way we try to do things everywhere else and allows for the 
      elimination of a clumsy mapping scheme in the FE routines themselves.  
      With the elimination of the need for building that scheme in each FE
      routine we can also stop passing around "old_numbers" for the
      most part. There is probably a very slight performance hit
      because now just about every analysis type should restore original
      node numbers in renumbered problems before they output any
      results (otherwise their references to analysis.nodes [i] -> number
      will refer to a node's renumbered number ...).  I got rid
      of MakeNodeNumberingMap() in renumber.c.
  18. added a NodeDOF data structure for use in the re-done FindForcedDOF
      and the accompanying spectral analysis routines ... this parallels
      what I did to the analysis nodes - removed references to node or
      DOF number and replaced them with pointers.
  19. I implemented the concept of "sub-analysis types" so that I
      could do load cases, parametric input ranges, etc.  What this
      means is that the user can still only say analysis=static, but
      depending on if any load cases are defined or if input-node and
      input-dof are given, the actual analysis type used will be
      StaticLoadCases or StaticLoadRange.  This means that driver
      routines should call mode = SetAnalysisMode ( ) and then switch
      on the local variable mode rather than problem.mode.  It's
      really a sort of behind the scenes output control ...
  20. cleaned up the printing of some of the analysis parameters on
      FElt file writing
  21. the new material properties for thermal analysis were not 
      being initialized
  22. fixed up some problems with incorrect numbers of arguments in 
      a couple of places in velvet
  23. the Cholesky factorization was actually returing a matrix 
      Q such that Q^T * Q = M, rather than Q*Q^T = M which is what
      the modal analysis routines were actually set-up to handle.
      This was producing incorrect results for problems with
      consistent mass matrices.  Thanks to Alvino Cossimo for pointing
      this out and for providing the appropriate fix.
  24. The geompack routines are flaking out for some reason that
      I still haven't really pinned down.  I think I have it at a
      point where they will work for problems with no holes all
      the time and for all problems when I turn off the optimization 
      in gcc.  Given that kind of behavior I wouldn't be surprised
      to hear about other machine specific strangeness ... if you 
      discover any let me know.  For now I'll just turn off the 
      optimization on any machines that it is causing a problem on.

The following features were added:
   1. the ability to plot force-time histories from the force
      dialog in velvet.  This means that for any given force
      you can see what your forces (moments) look like over 
      the course of your simulation.  It's really just intended
      to give you a visual check that you have defined it
      the way you actually wanted it.
   2. added a magnification parameter to WriteGraphicsFile( )
      which allows the routine to apply magnified displacements
      to the nodal coordinates if you want it to spit out
      a displaced shape plot.  Use 0.0 for backward compatibility.
   3. an axisymmetric element
   4. large deformation, incremental, nonlinear static analysis - sort of
   5. load cases - it feels kind of awkward right now but I couldn't
      think of any cleaner ways to do it.  Right now, you can define
      a series of named load cases.  For each load case you get
      displacement info at each of the analysis nodes and DOF.
      The load case definition itself consists of a series of
      (node number, force name) and (element number, distributed name)
      assignments (the element loads are ignored right now).
   6. logarithmic, sinusoidal, cosinusoidal, parabolic, reverse-logarithmic
      and reverse-parabolic spacing for mesh
      generation in corduroy.  The syntax for logarithmic had
      always been there but had never actually been implemented.
      The grid generation functionality was moved into a new
      dialog to be consistent with triangle generation and
      to allow for the selection of a given spacing.

      Here's how they work: along a line of length L along which we are 
      placing the sides of ne elements (ne+1 nodes), the i_th node is 
      placed at a distance x_i, according to the following rules

      linear:              L * (i - 1)/ne
      cosinusoidal:        L - L*cos(pi/2 * (i - 1)/ne) 
      sinusoidal:          L*sin(pi/2 * (i - 1)/ne) 
      logarithmic:         L*log10(1 + 9*(i - 1)/ne)
      parabolic:           L*((i-1)/ne)^2
      reverse-logarithmic: L - L*log10(10 - 9*(i - 1)/ne)
      reverse-parabolic:   L*sqrt((i - 1)/ne)

      I'm not sure how useful some of them are, but they generate
      some cool looking meshes.
     
   7. the ability to write out global matrices in matlab
      format from felt
   8. load ranges - because load cases were awkward :).  It came
      down to the fact that I could not see one all-encompassing,
      yet elegant, way to do everything I wanted to do with
      load cases.  To use load ranges all you need to do is define
      a single input DOF (with input-node= and input-dof=) 
      and then a force range (with start=, stop=, step=) and you
      will get displacement info at your analysis DOF (nodes=[], dofs=[])
      at each given load level.
   9. detailed solution information in many places.  A driver application
      can now turn on detail printing with a single call.  Analysis
      routines simply make calls to the new function detail() and
      if the printing flag has been toggled all sorts of ancillary 
      solution information can be spit out (renumbering info, iteration
      counts, matrix sizes, etc., etc.).  Of course not all routines
      have anything important to say.
  10. FElt -> OOGL translation in patchwork - thanks due to Stefan Majer.

The following things were changed for no apparent reason:
   1. the velvet color scheme.  I think the new subdued colors
      give us a more serious look.  The old scheme was really
      starting to get on our nerves.  I think we're also planning
      on linking statically against the Xaw3d widgets for as many
      platforms as possible.  Again, a more serious look.
   2. moved the etc/Tests directory to examples/


** Changes to FElt from 2.30 to 3.00 (released 8/6/95) -

The following changes were made to the FElt syntax:
   1. constraints can now have ITx= ITy= ... IRz= statements to define
      a set of initial displacements.  This means that we should now be
      able to completely and independently define both the initial and
      boundary conditions for a problem.  Tx= ... Rz= are the boundary
      conditions and ITx= ... IRx=, Vx= ... Vz=, Ax= ... Az= are the
      initial conditions.  I really should have done it this way from the 
      start and technically this fixes a bug that could well have cropped
      up in transient analysis problems with fixed (non-zero)
      displacement BCs.  Also note that the Tx=...Rz= statements can now be
      functions of time (i.e., expressions with t in them) just like forces
      can be.  This allows for time varying boundary conditions.  

      Is this backwards compatible?  Yes and no.  It allows for clarification 
      of an ambiguity between boundary and initial conditions (see #3 in
      bug fixes).  If you currently have problems with non-zero initial
      conditions then you WILL need to change those files and move the
      initial condition specification to ITx= ... IRz=.  If you had a
      problem where the Tx= ... Rz= were supposed to be boundary (as
      opposed to initial) conditions then chances are that you were not
      getting the right answer before, but you can leave the file as is
      and should get the right answer now.  I realize that this may
      cause some confusion (it did for me as I was trying to work it out)
      so just drop us a note and we'll try to clarify if you still have
      questions.
   2. nodes can now have a lumped mass assigned to them with mass=.  This will
      simply add this amount of mass directly to the translational DOFs
      for this node in the global mass matrix.  Completely backwards
      compatible.
   3. new analysis types are supported in the analysis= statement in the
      problem description section.  They are: spectral, static-thermal,
      and transient-thermal.
   4. changed the trig functions to take arguments in radians instead of
      degrees.  Yes, we thought that making them take degrees was a nice
      little feature when we only thought about them as an aid to defining
      the geometry of problems with funny angles ... but now it occurs to
      me that more people are probably using them for harmonic forcing
      in transient problems and for that, radians is the way to go. 
      Besides, everybody else does it that way so we probably should 
      have too right from the start.  This is _not_ backwards compatible
      obviously and I apologize if it causes anyone major headaches.
   5. added Kx, Ky, Kz (thermal conductivities) and c (heat capacitance)
      to the list of available material properties.
   6. added start=, stop=, step= to the analysis parameters.  stop and step
      are essentially aliases for duration and dt in a transient analysis
      problem; the new forms are preferred because they are more 
      general.  Things were generalized to make room for spectral
      analysis.
   7. added an Rk= and Rm= to the analysis parameters.  This allows for
      a global level of Rayleigh damping as opposed to an element by
      element (dependent on material property) definition.  If either 
      of these "global" parameters is given, then the global damping matrix
      will be based on them and any element by element results will be 
      thrown out.

The following bugs/things were fixed/changed:
   1. added a tabbing mechanism and keyboard translations to the line graph
      drawing shell (time displacement plots).  Honest, I think that's 
      the last pop-up shell that didn't have them :-))
   2. put AllocationError() back into misc.c ... don't ask me how it got
      removed in the first place.
   3. fixed the fact that fixed displacements were not being handled in
      transient analysis problems.  In previous versions I was treating
      the constraint specification (Tx= ... Rz=) as the both initial
      and boundary condition.  This could cause some real ambiguity issues
      if you wanted to specify both obviously.  With the current fix,
      Tx= ... Rz= are now interpreted as time varying boundary conditions 
      (i.e., they can have t in them) and the initial displacements are 
      explicitly specified using ITx= ...  IRz =.  See the note on syntax 
      changes to know if you need to update any of your input files.  
      If you had problems with non-zero IC then you probably do need to make 
      some changes (the IC specification should be moved off of of Tx=
      and onto ITx=).  Sorry for any confusion that this may cause, but
      really, I think it should be much clearer now.  Note that because
      I am now treating displacement BC properly, I had to modify the
      hyperbolic time integration implementation so that d(i+1) is solved
      for implicitly (as opposed to a(i+1)).
   4. renamed several functions and moved things around so that all of the
      ASCII output routines are now in lib/Felt/results.c instead of being
      spread over fe.c, modal.c and dynamic.c.  Renamed dynamic.c to 
      transient.c.  The functions which changed names are:

      WriteOutput		->	WriteStructuralResults
      ResolveConstraints	->	ZeroConstrainedDOF
      ResolveModalConstraints	->	RemoveConstrainedDOF
      NewmarkIterate		->	IntegrateHyperbolicDE
      BuildInitialConditions	->	BuildHyperbolicIC
      ResolveInitialConstraints	->	ResolveBC
      EltStresses		->	ElementStresses
      EltSetup			->	ElementSetup

      Note that ZeroConstrainedDOF can now take NULL for the two
      force vectors if you only want to zero out the rows and columns
      in the stiffness (or any other) matrix.  Also ResolveBC does not do any 
      zeroing out of the stiffness matrix.  All it does is make appropriate 
      adjustments to the force vector for displacement boundary conditions.
      I also got rid of CheckModalAnalysisParameters and changed
      CheckAnalysisParameters to take an AnalysisType argument and
      check the parameters based on the given analysis type.
      The upshot of all this is improved clarity I think (plus it forced me
      to clean-up/organize the prototypes in fe.h).
   4. in yet another case of fiddling with graph.c I cleaned it up some
      to make it more robust in terms of plotting both transient structural
      and transient thermal results (i.e., made labels a parameter instead
      of hard-coding them, etc.).
   5. for Burlap's sake we got rid of ElementArray and changed the way   
      that applications know about the list of available elements.  The
      element definition structure changed such that the element name,
      and pointers to the setup and stress functions are included right
      in the definition structure.  See the updated chapter on adding 
      new elements for details on how this affects any elements that you
      have written.  For clarity, src/Velvet/definitions.h was renamed
      src/Velvet/interface.h so as to not conflict with the new 
      inc/definition.h file.  inc/element.h is gone completely.  When
      you add new elements just add the file name to the list of objects
      in lib/Elements/Makefile and update the initialization procedure in
      lib/Felt/initialize.c.  There is no separate element configure
      script that needs to be run and no elements.db file.
   6. corduroy's debugging option wasn't handling the fairly recent addition
      of quadrilateral grid generation.  It also wasn't printing out
      the element type names for each different generation section.
   7. added a dosdist target to the Makefile to create a zip file of
      the source needed for the command line applications.  I also
      patched up several different bits of source to check if the
      pre-processor symbol DOS is defined to make building DOS binaries
      less painful and easier for someone else to try.  
   8. in a final(?) fit of messing with graph.c, I made things lots more
      robust to make room for plotting power spectra (i.e., the x axis can
      now be something arbitrary not just nicely spaced time points, all
      the routines now take the graph structure/shell/drawing widget as a
      parameter so we can have both power spectra and time domain answers
      on screen at the same time).
   9. another round of major cleaning - this time in the form of abandoning
      the paradigm of passing around node, numnodes, dofs, count, etc.
      everywhere.  There are now two dofs arrays in the problem structure:
      problem.dofs_pos is the same as the old dofs array, problem.num_dofs
      is the same as the variable count that used to get passed around,
      the new array is problem.dofs_num and it gives the local DOF
      number (1 through 6) of an active DOF in the problem, i.e., for
      a mixed beam truss problem the two arrays will be

      problem.dofs_num = [1, 2, 3, 6, 0, 0]
      problem.dofs_pos = [1, 2, 3, 0, 0, 4] 
      
      The new one also allowed me to rewrite the way that various routines
      search through the active DOFs on a given object for a given node
      to fill in global arrays. There are also two new routines 
      GlobalDOF and LocalDOF which map between node number, local DOF and
      a global DOF number.  Routines that need to access the node and element
      arrays can simply get to them through the problem structure.
  10. InvertMatrix was broken (sort of).  It's fixed now but the calling
      sequence of some things may have to change because it can't trash
      it's input anymore.
  11. added ZeroConstrainedMatrixDOF and RemoveConstrainedMatrixDOF for
      burlap's sake.  Both are much like their more specialized counterparts
      but are meant to be more generalized.  They only work on one matrix
      at a time and the input can either be a full, compact or column
      matrix.  They'll just do the right thing depending on the input.
  12. modal results now print the frequency in Hz in addition to the radial
      frequency.
  13. for consistency's sake you can now draw a polyline tool object
      with keyboard input (i.e., by inputting a series of coordinates).
      Also, esc/quit button and ctrl-c/abort button should now work during  
      polygon draw operations either during keyboard or mouse controlled
      draws.
  14. in order to keep things clear and to be consistent
      with the change to the syntax, the analysis structure members
      duration and dt were renamed to stop and step.
  15. renamed WriteModalResults to WriteEigenResults.  WriteModalResults
      is now a function to print out modal mass, stiffness and damping
      matrices (and modal damping ratios).  
  16. eliminated the -printk and -printm options from felt (and the
      output control in velvet) in favor of -matrices which simply
      prints out whatever matrices are appropriate to the problem.
      Also, I wrote PrintGlobalMatrices to keep the solution drivers
      from getting cluttered up - it will check for matrices of all
      zeros as well; each analysis type in a switch now just needs to
      check for the matrices flag and call this new function as
      appropriate.
  17. lots of minor cleaning to get gcc -Wall to shutup and some
      rearranging of various bits and pieces - nothing really at the
      user level though.  The Makefile scheme also got reworked.
      Oh yeah, we completely removed xfelt from the distribution.
      If you really, really want it and you don't already have it 
      from one of the previous distributions (it hasn't change since
      about v1.3 I think) then drop us a note and we'll get it to
      you somehow.
  18. looks like the velvet distributed load dialog was doing some
      funny things with a few malloc's so things may have been getting
      garbled.

The following features were added:
   1. burlap - yes, it's finally here.  Our very own attempt at a
      powerful, flexible, easy-to-use interactive environment for doing
      FEA, burlap lets you script new analyses and new elements; it lets
      you use the results from current analyses in ways that we didn't
      think to provide in one of the other applications; it's sort of a
      FE-aware Matlab-like application.  There are two brand new chapters in 
      the manual that describe it - yes, it's that big and that powerful.
   2. thermal (heat transfer) analysis, both steady state and linear time
      dependent forms.  Two new elements are available for these analyses:
      a constant temperature gradient triangle (analogous to a CST), and a
      one-dimensional rod (sort of like a truss, only simpler in that rod 
      elements can only really exist along a single line because there is no 
      transformation matrix applied).
   3. added user contributed elements to the standard distribution. This
      currently adds a triangular plate bending element (PLTGZ4) to the 
      element library if you answer yes to the new question in the configure 
      process (the one about building user contributed elements).  
   4. corduroy can now generate a grid of brick elements.  This isn't really 
      anything special but it does allow for a simplistic meshing of a 
      rectangular solid of some kind.  Chapter 8 of the manual has been 
      updated to reflect the changes.  Note that because velvet does not have
      a mechanism for specifying coordinates in 3d, velvet cannot generate
      these kinds of grids.
   5. spectral analysis.  Just take what used to be an analysis=transient
      statement and make it an analysis=spectral statement and watch the
      fun (of course you really should change the duration and dt into 
      start, stop and step frequencies and change forces to their frequency
      domain analogs if you want output power spectra as opposed to just
      transfer functions).  The output will be the frequency domain analog of 
      the results that you normally see for transient analysis problems.  As 
      usual regular old ASCII results are the default but both felt and velvet
      can plot the power spectra or transfer functions if you want graphical 
      results.  If you give felt the -transfer option then it will only
      calculate transfer functions; if not then it will want frequency
      domain forces to be applied and it will calculate output spectra instead.
      The transfer only option is also a new toggle in the output/results
      dialog under the solutions control menu in velvet.
   6. now clicking on the third mouse button (right button) on a node
      or element raises both the node (or element) dialog plus the
      appropriate object dialogs with the objects assigned to that
      node (or element) already highlighted, i.e., this is an easy
      way to change the actual definition of a force that is assigned
      to a node (keep in mind however that objects can be assigned to 
      more than one node or element so any changes you make could affect
      other nodes and elements).
   7. added modal analysis to modal analysis ... what this really means is
      that I went ahead and added some capabilities beyond just finding
      the eigenvalues and eigenvectors.  You can now calculate the 
      modal mass, stiffness, and damping matrices.  You can also just stop
      at the eigenvalues and eigenvectors if you want to using the
      -eigen switch in felt.  felt also has a new switch (-ortho) to control
      the use of orthonormal mode shapes.  Both switches are also available
      in the revamped output/results dialog available from the solutions
      menu in velvet.
   8. added a -preview option to felt.  It tries to draw an ASCII rendering
      of the structure described by the input file.  It's far from 
      perfect but for a lot of structures it may be enough for a quick
      check of the validity of the problem geometry.
   9. a very simple, one-dimensional spring element was added.  It's 
      basically the truss without a transformation from local to global
      coordinates; they should only ever be defined along the global
      x axis.
  10. added "ctrl-t ?" keyboard shortcuts for the drawing tools (ctrl-t c
      for a circle for instance; ?=l for line, ?=t for text, ?=p for polygon,
      ?=r for rectangle, ?=a for arc).
      
** Changes to FElt from 2.23 to 2.30 (released January 18, 1995) -

The following bugs/things were fixed/changed:
   1. planar elements were drawn all wrong during animation
   2. changes to a parameter for a material property after already having 
      solved the problem once were not properly reflected in subsequent solves.
      The bug was in something the element library was doing but only really
      showed up in velvet.
   3. The original shape for 3d wireframe plots was still being drawn in
      yellow rather than with a dashed line like it should have been based
      on the changes from 2.0 to 2.1.
   4. The initial implementation of the lumped mass matrix for beams did
      not calculate an inertia for rotational DOF.  In playing around
      with modal analysis I noticed that we should probably put something
      in there for consistency with the kinds of answers that most people
      expect to get.  Changed for beam3d and timoshenko elements as well.
   5. stiffness matrices and material statistics were only printed in
      static analysis problems.  Mass matrices can now be printed for
      both transient and modal analysis problems as well.  Note that the
      stiffness and mass matrices for modal analysis problems are completely
      condensed (i.e., constrained DOFs are completely removed from the 
      problem, not simply zero'd out).  This is one way to look at the 
      same kind of stiffness and mass matrices for a problem that you are
      also doing by hand (in assembling by hand of course, few if any of of us
      actually bother to assemble the constrained DOFs in the first place).
   6. the contour field drawing routines wasn't cleaning up properly if an
      error occurred in the middle of the interpolation process.
   7. moved the velvet routines in misc.c into text_entry.c and group.c 
      to better reflect exactly what they did.  misc.h is now text_entry.h
      because it only had prototypes for the text stuff.
   8. I changed the matrix printing routines to make the output look more
      like some other programs that pretty print matrices ... I think it's
      more readable this way.
   9. fixed scaling problems in structure/animate plots when the structure
      only existed in one dimension (i.e., a line).  Also fixed the  
      problem of the animation widget resizing itself too small on 
      tall, slender structures (in essence it was not trult consistent with
      the new plotting method of resizing/clicking/drawing ...).
  10. added a tabbing mechanism and keyboard translations to the animation
      pop-up shell.
  11. I actually wrote a new README for this release.  I've also moved all the
      old README (alpha, 1.3, 2.0) into a single file: README.old
  12. slight fix-up to the configure script so it looks for /usr/X11R5 and
      /usr/X11R6 for X includes and libraries.
 
The following features were added:
   1. a three-dimensional solid, 8-noded brick element was added to the
      element library.  See chapter 3 of the updated manual for details on
      how to use it.  There is a very simple example in etc/Tests/brick.flt.
      For the most part, brick elements will be hard to use in velvet 
      because of velvet's problems with drawing and defining a problem in
      3d.  However, the wireframe structure plots (under post processing ...)
      have been modified and should be able to handle basic rendering 
      of problems with bricks in them (no hidden line removal though ...).
      Animation and mode shape plots still don't work for these.
   2. a basic form of modal analysis has been added.  Change the analysis=
      to modal in the problem description section and FElt will calculate
      the eigenvalues and eigenvectors for the problem.  See modal.flt
      in etc/Tests and the new section at the end of chapter 2 in the manual.
      Some velvet specific notes have been added in Chapter 7 (there were
      changes to the problem/analysis and output control dialogs).  I also
      added a section in chapter 9 to describe the numerical procedure FElt
      uses to actually solve the generalized eigenvalue problem.
   3. a version flag to felt.  I also added inc/version.h to help keep this
      updated here and anywhere else it might be needed.
   4. examples that illustrate multiple distributed loads on an element
      (etc/Tests/dist_mult.flt) and a simple simply supported beam
      (etc/Tests/beam_ss.flt).  
   5. replaced GIF support with PPM support for saving images of contour
      plots.  Though PPM is perhaps not as widespread, it is fairly well
      supported between pbmplus and xv.  If nothing else, pbmplus gives you 
      the power to translate to just about any other format you could think of.  
      Note that PPM images can get pretty big, pretty quickly; you'll
      probably want to convert to a compressing format or simply compress
      the actual PPM file with something like gzip.  The reason for the change
      should be obvious with all the current hoopla about CompuServe and
      their attempted restrictions on the use of GIF - we simply figured
      why bother with it.  We figured that EPS (see next note) and PPM
      would be good enough for now and we'll think about changing it again
      once some sort of simple 8-bit standard image file format begins to
      emerge.  
   6. encapsulated postscript support for saving contour plots.  I also
      hacked up the file dialog yet again to make it more robust in terms
      of having arbitrary labels on the toggles (i.e., XWD/PostScript vs.
      PPM/EPS). 

** Changes to FElt from 2.22 to 2.23 (released September 7, 1994) -

The following bugs were fixed:
   1. the problem title was not being set properly in the problem/analysis
      dialog box.
   2. a transient analysis problem with no nodes or DOFs defined didn't
      save right from velvet (and therefore did not load back in either).
   3. changed the animation and drawing popup shells to topLevel class from
      transient because some window managers actually do some things right
      and don't allow you to resize transients ...
   4. invalid node numbers in a distributed load on a CST could produce core 
      dumps because the error checks were being done in the wrong order.
   5. the heuristic for deciding how to orient the wedge on a stress or a 
      displacement plot was not self-consistent throughout the plotting
      routines and in some cases this caused the scale to draw on top of
      the actual plot.
   6. corduroy did not put the problem description section on top of the
      output so the resulting file could not be used directly in velvet.
      There may have been some reason for this initially, but I can't think
      of what it was now and it struck me as kind of annoying when I came
      across it.
   7. the mass matrices for HTK plate bending elements were wrong (I think).

The following features were added:
   1. corduroy and velvet can now generate a grid of quadrilateral elements.
      This isn't really anything special but it does allow for a simplistic
      meshing of a rectangular plate of some kind.  Chapter 8 of the manual
      has been updated to reflect the changes.

** Changes to FElt from 2.21 to 2.22 -

The move to 2.22 involved purely structural changes and minor fix-ups to
allow for cleaner compiles on different platforms using a couple of 
different compilers.  The most visible change is the renaming of bin
to src for consistency with current trends in other software packages.

** Changes to FElt from 2.20 to 2.21 -

The following change was made to the FElt syntax:
   1. materials, constraints, loads and forces can all now have a color=
      parameter to control the new multi-color rendering in velvet.  In
      general the parameter would only get set by velvet during a save so
      that colors would be maintained when the file is read back into 
      velvet.  Other FElt applications will effectively ignore the color=
      entirely.  The change is completely backward compatible of course.

The following bugs were fixed:
   1. The wrong menu was left sensitive during edit operations.  You should
      have access to the canvas menu not the post-processing menu during
      an edit.  Also made the four object pop-up menu controls sensitive
      during edits to make it easier to change the active constraint, etc.
      in the middle of an add operation and cleaned up the stuff that
      should always be sensitive in the Canvas menu.  
   2. Reading in a material database didn't automatically update the material
      list in the element dialogs.
   3. Changing canvas parameters in the middle of adding nodes / elements 
      was not immediately reflected in the additions after the change was
      made. 
   4. Moving the first node of a line element caused that element to be
      drawn improperly (such that it looked like it wasn't drawn at all).
   5. renamed the actual executable filename of patchwork to patchwork
      (instead of pw).  This means that if you ever actually installed
      FElt-2.20 you should be sure to clobber the pw executable because the
      new one will not overwrite the old one.  Sorry about that.
   6. mass of truss elements not entirely in the z-plane was not properly
      calculated.
   7. saving a problem with no nodes or elements caused a core dump.
   8. saving more than one GIF plot during a single session tended to be
      unreliable ... If anyone ran into a problem where the _first_ GIF saved
      was somehow corrupted then we'd like to hear about it because that may
      be a separate bug.

The following features were added:
   1. A unique color can be assigned to each material, load, constraint, force.
      This means that in velvet, elements (nodes) with different material 
      properties (constraints) can be rendered in different colors.  If
      an element (node) has a load (force) assigned to it then the load
      (force) coloring will override the material (constraint) color.
      The coloring for all objects is controlled from a single dialog 
      accessible via the canvas menu.  
   2. The way that post-processing windows get sized was changed to allow for
      more user control.  Now when you plot something the first thing that 
      happens is the window comes up blank.  You can resize this window 
      as appropriate.  The plotting won't start until you click in the 
      drawing area (the big blank white space); once it does start it will
      use whatever size you had the drawing area when you clicked.
   3. Unified the code for the post-processing drawing shells and added
      tabbing mechanisms and keyboard translations to them.  The layout
      widget is also now responsible for their geometry management. 
   4. A unit conversion and problem scaling application called 
      yardstick.  See the new subsection on units in chapter 2 and the
      new manual page for details.

** Changes to FElt from 2.16 to 2.20 -

No changes to the FElt syntax.

The following bugs were fixed:
   1. the install target didn't install anything from bin/Corduroy ... oops
   2. a couple of tweaks were made to allow for easier compiles on certain
      machines.  see new special instructions at the end of the INSTALL file.
      Some of these tweaks/instructions should allow for compilation of
      FElt on systems with X11R4.
   3. resolved the problem of circular dependencies between libelt and libfelt.
      All of the basic matrix routines are now in lib/Matrix ... we did
      a new library for a new application that's in the works so we might
      as well use it for everything else.  A couple of utility routines
      also got moved ... ElementArea ( ) is now in lib/Elements/misc.c, 
      ZeroRowCol ( ) is now in lib/Elements/misc.c.  The new matrix library
      has more transparent sort for compact column matrices so some of 
      the details of routines in fe.c and dynamic.c changed.  We probably
      introduced a few bugs by changing a major component of the mathematical
      routines, but oh well, it's all in the name of progress, we promise.
   4. the configuration process was changed - building xfelt is now an option
      and the default is no.  With velvet available and xfelt not having
      changed in several releases, we see little point in building it over
      and over again.

The following features were added:
   1. a new application, patchwork, was added to the system.  patchwork 
      allows you to convert files from other packages to the FElt syntax (and
      vice versa).  Right now it can read FElt, AutoCAD-like DXF files, and
      gnuplot data files and it can write FElt, DXF, gnuplot data, and files 
      formatted for the software in Logan's book.  There's a new section at 
      the end of chapter two of the manual with some more details.
   2. The bulky solution/output dialog box was broken up into three new
      dialogs: one to toggle solution output and one each for contour plotting
      and structure plotting.  The latter two allow more control than was 
      previously available for the post-processing options.  The new output
      toggling mechanisms also now mirrors all of the command line options
      available in felt (i.e., printk and debug are now implemented).
      The postprocessing options and controls were moved from the solutions 
      menu to a new menu called, appropriately enough, postprocessing.
      The problem title and analysis mode were moved to the analysis 
      parameters dialog box - this one dialog now is exactly analogous to
      the problem description and analysis parameters section of the
      FElt syntax.  The renumber toggle button (for temporary renumbering
      during solutions only) was moved to a menu based switch on the nodes
      menu.

** Changes to FElt from 2.15 to 2.16 -

No changes to the FElt syntax.

The following bugs were fixed:
   1. hitting quit with no boundary markers during element generation in
      velvet caused some really stupid errors - even core dumps.  
   2. plotting stress contours for a problem with all zero stresses 
      caused floating exceptions (surprise, surprise).
   3. plotting structure plots by doing a plot structure on solution from
      the output dialog box either didn't work right or core dumped
   4. plotting anything for iso2d elements was generally pretty screwed up
   
The following features were added:
   1. the ability to move tool figures around the drawing area in velvet -
      simply select move from the tools menu, click on the figure to relocate,
      move it around, and click again to drop it in the new position.
   2. feature or bug-fix?  iso_quad elements actually define a mass matrix
      now during transient analysis (always lumped)
   3. a bindist target was added to the main Makefile to simplify making
      binary distributions

** Changes to FElt from 2.1 to 2.15 -

No changes to the FElt syntax.

The following bugs were fixed:
   1. Trying to plot stresses for an invalid stress component probably 
      produced unpredictable results as we weren't checking for this.  Now
      velvet should (rightly) report an error when you give a stress 
      component that is out of range.
   2. There is better colormap handling - if it can't get 128 colors it will
      use (and most importantly make maximum use of) what it can get.  It
      also warns when it only get 64 colors or less (half of what it
      wanted to get).  The results could get kind of screwy previously.
   3. The first time you type make it should check to see if you have done
      a make config or not - if not it will force you to do one.  We also
      removed the etc/config.in file so the make config should now do a 
      better job of guessing what local defaults should be.

The following features were added:
   1. A new plate bending element was added, with symbolic type name
      "htk".  It has four nodes (where the fourth can be the third repeated
      for degeneration to a triangle), and 3 DOFs (Tz, Rx, Ry).  The 
      internal forces calculated are M11, M12, M21, Q1, and Q2. Distributed
      loads on these still aren't operational. There is an example in 
      etc/Tests/htk.flt.
   2. The ability to do color shaded contour plots of nodal displacement
      components for planar elements.  (Just like stress plots).  This is
      one good way to visualize the Tz DOF of a problem with the new htk 
      elements.  The solution control dialog was modified to handle the
      controls of these plots.
   3. Dumping any of the color contour plots now produces a GIF file instead
      of an XWD.  The theory here is that GIFs are easier for most people
      to work with - plus you don't have to worry about whether or not the
      window is obscured when you click on OK in the file dialog.

** Changes to FElt from 2.0 to 2.1 -

The following changes were made to the FElt syntax:
   All changes are completely backward compatible in this release - all
   original v2.0 (or v1.3 even) problems will not need any modifications.

   1. addition of canvas configuration and display list sections to 
      standard FElt syntax to replace the .vlv files.  Now all of the
      customization for problem appearance and tool figures is stored
      directly in a plain-text format right within the standard FElt
      file.  If these sections are present and felt is used on the problem
      they are simply ignored.  If velvet is used to read the file then
      this info will be used to restore the canvas to its previous
      appearance and to reconstruct all of the tool figures.

The following bugs were fixed:
   
   1. cpp_args was not initialized in problem.c (ParseCppOptions) which
      broke the file handling on a DEC Alpha (thanks to Sanjay Gavindjee)
   2. some very early editions of v2.0 that may have gone out did
      not properly read from standard input.

The following features were added:
   
   1. PostScript output in canvas dumps, structure plots, etc.
      A mod to the file dialog to allow for optional toggle buttons
      which control whether the user wants XWD or PS output.
   2. line styles went into the drawing widget.  In structure plots
      this means that the original undisplaced structure is drawn
      with a dashed rather than a yellow line.
   3. renamed the Problem ... menu to Solutions ..., renamed Define ...
      under this menu to Output ... in an attempt to be more explicit
      about what those options actually do.  Dump ... under Canvas ...
      was renamed to Save canvas ...
   4. graphical time-displacement plots in place of the regular felt
      output ascii versions ... much nicer and they save as PostScript 
      plots that print really well.
   5. elimination of those damn .vlv files in favor of additions to the
      FElt syntax to describe all of the canvas and tool stuff in plain
      text.  (see above) 
   6. the cursor in the main drawing area changes to a watch during
      computational waits now (ooh, ahhh).
   7. corduroy ... no really now, it's actually a complete program
      that actually works. (see the new chapter in the manual)
   8. in that same vein, a routine to coalesce nodes was incorporated
      into all the generation stuff.  What this means is that you 
      should now be able to get away with generating elements in
      adjacent regions at two different times, etc.  Nodes that are
      very near to each other, but are not connected (i.e., because
      you generated a bunch of elements and nodes and then went back
      and did the same thing right near or next to the first bunch)
      will be merged together.

** Changes to FElt from 1.3 to 2.0 (released February 12, 1994) -

The following changes were made to the FElt syntax:
   All changes are completely backward copmpatible in this release - all
   original static problems will not need any modifications.

   1. t is now a valid token in expressions.  In a transient analysis problem
      it will stand for time in a force and be dynamically evaluated throughout
      the course of the simulation.  In static problems it will simply
      be evaluated at t=0 at startup and treated as a constant expression.
   2. valid expressions can now use the intrinsic functions hypot, log, 
      log10, ceil, floor, fmod, fabs, exp and pow.  They can also make use of
      the C style ternary if-then-else operator (t < 10 ? 15*t : exp(-0.03*t))
   3. a mechanism for time-magnitude pairs for discretized dynamic forces
      was added.
   4. an analysis= parameter in the problem description section to control what
      type of analysis is performed (static or transient) for that problem.
      The default is static if nothing is specified.
   5. an "analysis parameters" section to control the variables in 
      transient analysis problems - beta, gamma, and alpha are parameters
      in the HHT integration scheme.  duration and dt control the length
      and the time-step of the integration.  nodes= and dofs= control
      what node (and which DOFs at each node) are included in the output.
      mass-mode= controls what type of element mass matrices should be formed, 
      either consistent or lumped.
   
The following bugs were fixed:
   1. a couple problems with trying to solve problems (or do anything for that
      matter) after you'd deleted elements in velvet.
   2. the variable 'time' in lib/Widgets/post.c was renamed 'when' to avoid
      conflicts with some installations of gcc
   3. a local implementation of strdup was provided for systems that insist
      on being totally and solely ANSI and POSIX compliant.
   4. delete window hooks were added to the post-processing popups so you
      can now close them with the window manager and the entire program
      won't crash.
   5. a bug? ... well, the Fortran compiler was taken out as an option in
      the configuration - it's just too confusing for people as most people
      do not know what the extra libraries are that they need to link in.
 
The following features were added:
   1. transient analysis using Hilbert-Hughes-Taylor alpha variant of
      Newmark integration.  The C and M matrices are also assembled directly
      into a compact column representation.  Dynamic forces can be specified
      as continuous functions of t (see syntax changes above).
      -plot and -table options were added to felt to control the output.
   2. direct assembly into compact columns for the K, M and C matrices - this
      can represent a major savings in memory.
   3. automatic node renumbering for bandwidth/profile reduction of the
      matrices - in felt it is activated by a command line switch;
      in velvet you can do it once and for all and the way your problem
      is shown and saved will reflect the new numbering or you can implement
      it with a toggle as in felt that just does it to solve the problem
      and then reverts back to the old numbers to show you your solution
   4. renumber and summary toggles were added to the solution dialog in
      velvet to mirror felt command line options.  plot and table toggles
      in that same dialog reflect new command line options in felt that control
      the output for a transient analysis problem.
   5. static and transient mode analysis toggles in the solution dialog
      to control the problem mode (equivalent to analysis= in the problem
      description section of a FElt file).
   6. an analysis parameters dialog box to account for the new section
      in the FElt syntax.
   7. animation of transient analysis simulations as a special case solution
      mode for these types of problems.  The animation popup includes controls
      for speed, play forward/backward, stop and a time counter. 
   8. the ability to evaluate an expression wherever velvet is expecting a
      floating point number in a dialog box (i.e., forces, material properties,
      nodal coordinates) just like you can use an expression in the regular
      FElt syntax, including the variable t in dynamic forces.
   9. element mass matrix (consistent and lumped) definitions for truss, 
      beam and timoshenko elements.  Only lumped mass formulations are done
      for beam3d and cst elements.  Nothing is done for isoparametric 
      elements.

** Changes to FElt from 1.0a to 1.3 (released November 7, 1993) -

The following changes were made to the FElt syntax:
   1. addition of 'hinge' or 'h' as a keyword after the R[xyz]=
      token in a constraint to indicate a hinged DOF
   2. addition of a valid expression after the T[xyz]= or R[xyz]=
      token in a constraint to indicate a displacement boundary  
      condition.  Tx=c for examples is now equivalent to Tx=0.0.
   3. directions 'x','y', and 'z' are no longer valid.  This is
      the only backward incompatible change to the syntax.  Valid
      directions now include LocalX, LocalY, LocalZ, GlobalX,
      GlobalY and GlobalZ.  Check the element definitions in the
      user's manual to see what these things mean.
   4. you can now use sqrt() in expressions (just like you   
      you could use sin, cos and tan before).

The following bugs were fixed:
   1. a bug in xfelt which caused a core dump when you tried to
      draw a problem in 3d when it was only a 2d problem.
   2. a bug in the internal forces calculated for beams which always
      caused the second end moment to be printed as zero.
   3. several bugs in 3d beam elements including an error in the
      global <-> local transform matrix and a typo in the resolution
      of distributed loads.  I think they actually work now :-).
   4. not really a bug, but the directions of loads on beam elements'
      got straightened out and is probably a bit more consistent now.
   5. consistency amongst text commands, menu options and keyboard
      shortcuts was substantially improved.
   6. does the original user's manual count as a bug?  Well the new one
      should actually print on any old postscript printer, plus it
      contains a wealth of new information and is organized a whole lot
      better.

The following features were added:
   1. hinged DOFs, displacement boundary conditions.
   2. a simple, illustrative Timoshenko beam element.
   3. plotting of 2d planar stress fields with color imaging in velvet.
   4. plotting of the displaced structure in velvet.
   5. loads directed along the global coordinate axes on beams and beam3ds 
   6. a real file selection mechanism for velvet
   7. much improved, consistent, self-contained force, material, 
      load and constraint dialogs in velvet
   8. unified node and element edit/info dialogs
   9. a problem solution control dialog in velvet
  10. unified interface mechanism for all the dialogs, including tab groups
      and the ability to leave dialogs up throughout a work session
  11. translation include files and a built-in include path for cpp
      in felt and velvet.
  12. element numbering