Version 6.51   07/24/19

• Corrects error in update check when registered to a V7 dongle.
• Corrects an error in non-gui update check so doesn't wait for input.
• Implements CABS, complex absolute value function.
• Diagnose table references outside of range.
• Define ATAN2V6 so same script can be run on versions 6 and 7.
• Corrects other miscellaneous errors.

 Version 6.50   02/01/17

• Corrects miscellaneous errors in matrix handling.
• Adds CodeMeter dongle functionality to support reading a FlexPDE 7 dongle. (Windows and Linux 64-bit only.)

 Version 6.40   09/20/16

• Corrects occasional "Constant required" errors for regionally dependent parameters.
• Improves speed of calculation for nested parameter dependencies.
• Corrects occasional error in TRANSFER of meshes with JUMP boundaries.
• Corrects multiplicative distribution of expressions containing LAMBDA.
• Implements TRANSPOSE for tensors.
• Adds command-line switches for licensing operations.

 Version 6.39   04/18/16

• Improves TRANSFERMESH lookups, especially at interfaces with discontinuous data.
• Corrects an error in LIMITED FEATURES on SURFACES.
• Corrects implementation of tensor = vector * vector.
• Corrects LINE_INTEGRAL in 1D problems to properly use the VOLUME_INTEGRAL.
• Corrects the EXPORT of ELEVATIONS with more than 65,000 data points.
• Adds the MERGEDIST used to the generated script when importing 2D DXF files.
• Correctly initializes data for INITIAL VALUES that reference a SAVE.

 Version 6.38   10/07/15

• Improves gridding of regions that form "hourglass" pinchouts.
• Improves diagnosis of plots without a time selector.
• Corrects implementation of imbedded NATURAL bc on JUMP boundaries.
• Other miscellaneous fixes.

 Version 6.37   02/12/15

• Adds a diagnostic for a bad layer count when reading DXF files.
• Corrects the behavior of WINDOW (t1,t2) to display fixed range of (t1,t2).
• Implements the power of a COMPLEX number.
• Expanded maximum THREAD count for a script to 24.
• Corrects the derivative of a UPULSE function.
• Corrects an error in the classification of products of COMPLEX numbers.
• Corrects an error in the TRANSFER of regionally constant data.
• Corrects an error in GLOBAL VARIABLES when only coupled to VARIABLES through NATURAL boundary conditions.

 Version 6.36   07/29/14

• Corrects an occasional error in TABLE smoothing.
• Corrects an error that caused an EXPORT of a HISTORY to append data rather than rewrite the file.
• Corrects an error that prevented the use of "thin" in graphics exports.
• Implements complex functions CABS and CSQRT.
• Implements the time derivative of a time integral (TINTEGRAL).
• Implements GLOBALMAX_X, etc. in AT specifications for HISTORY plots.
• Implements color selection for the script display by manually editing the flexpde6.ini file (e.g. for color blind users).

 Version 6.35   02/17/14

• Corrects an error in elevation plots with a negative start point.
• Corrects an error in displaying eigenvalue list reports (introduced in 6.34).
• Corrects an occasional error in matrix symmetry checks.
• Corrects an occasional error in rerun on some systems.
• Corrects a potential error in the use of CRITICAL TIME.

 Version 6.34   01/21/14

• Adds extended string syntax in #INCLUDE names to allow $ expansions and catenation.
• Corrects and occasional divide by 0 in eigenvalue problems.
• Retains proxy server information when deselected.
• Corrects occasional errors in power operations.
• Diagnose contact boundary conditions applied to exterior boundaries.
• Corrects occasional error in applying boundary conditions in corner cells in 3D.
• Corrects error in closing View tabs, making remaining tabs inaccessible.
• Corrects error in handling INACTIVE variables at contact boundaries.
• Improved test for matrix asymmetry.
• Corrects error in assigning initial values to VECTOR VARIABLES.
• Corrects a floating point error in plots using an extremely small RANGE.

 Version 6.33   07/25/13

• Corrects an update error in play back of PG6 files (introduced in v.6.30).
• Allows sum and difference of integrals in constraint equations.
• Adds double-click and drag-and-drop handlers for Mac versions.
• Corrects an error in the movie export function (introduced in v.6.30).
• Corrects occasional error in boundaries with rotated ellipses.
• Adds diagnostic for illegal derivatives of the VAL function.
• Adds the DELETE selector to allow the automatic deletion of specified output files.
• Corrects an error in handling of GLOBAL equations in moving mesh problems.
• Corrects an error when a script ends inside a multi-line comment.
• Corrects various minor errors.

 Version 6.32   10/12/12

• Corrects a periodic gridding error (introduced in v.6.30).
• Corrects an error in the handling of the -T command line option (introduced in v.6.30).
• Corrects an error in the handling of missing script files given on the command line when using the -S option (introduced in v.6.30).
• Corrects and error in the handling of the executable file path on Mac OS X when running from the command line (introduced in v.6.30).

 Version 6.31   09/28/12

• Corrects a busy wait causing processor use during idle state (introduced in v.6.30).
• Corrects a random freeze when attempting to report a parse error (introduced in v.6.30).

 Version 6.30   09/17/12

• New FlexPDE6n executable that does not use any graphical interface.
• Implements PERIODIC boundaries in 1D.
• Implements ON GRID plots in 3D.
• Removes over-zealous error diagnostic that prevented using TRANSFERMESH in moving mesh problems.
• Allows scripts to request smaller initial time step than that imported by TRANSFERMESHTIME.
• Corrects an error in exporting more that ten data items in one EXPORT.
• Corrects an occasional error in 3D mesh generation.
• Corrects an occasional error in Save As.
• Improves handling of contact boundaries with partial extent.
• Improves handling of surface normals in some conditions.
• Improves handling of coordinate dependences in moving mesh problems.
• Improves handling of movable point references in EVAL statements.
• Improves diagnostic of partially merged extrusion surfaces in 3D.
• Minor changes to mesh generation logic.

 Version 6.20   11/23/11

• Removes regridding ban on 3D problems with contact boundaries.
• Adds a diagnostic for fractional power of a negative number.
• Improves handling of multiple boundary conditions at CONTACT joints(2D) and edges(3D).
• Improves handling of Tangential operator in 3D.
• Improves expression simplification procedures involving UNORMAL operator.
• Corrects an error when using GLOBAL VARIABLES with THEN equations.
• Corrects an occasional error that caused a crash on rerun after an illegal symbol report.
• Deleted INTSTRING operator. Use $ instead.
• Adds a diagnostic to enforce monotonic increasing TABLE coordinates.
• Adds a selector (FEATURE_INDUCTION) to supress cell-size induction loop in domain generation.

 Version 6.19   06/23/11

• Corrects a convergence difficulty affecting some nonsymmetric steady-state problems (introduced in version 6.16).
• Implements tensor operations DOT(tensor,tensor) and DOT(tensor,vector) and tensor component selectors XXCOMP()...ZZCOMP().
• Implements vector*vector producing a tensor.
• Implements tensor**tensor, equivalent to DOT(tensor,tensor).
• Corrects an error in computing VALUE boundary conditions on an interface between Active and INACTIVE regions.

 Version 6.18   06/09/11

• Corrects grammatical errors processing boundary conditions in 1D problems with array variables.
• Corrects error in plot levels when requesting less than 10 levels.
• Corrects node-positioning error in refining cells on curved boundaries.
• Corrects CDF export to write separate files for eigenvalue runs.
• Corrects treatment of inactive variables in 3D.
• Corrects an error (introduced in v.6.16) that sometimes caused an infinite loop in periodic problems.
• Corrects error in periodic problems with self-periodic cells.
• Corrects plotting errors in staged eigenvalue problems.

 Version 6.17   04/25/11

• Corrects application of sidewall boundary conditions to edges when surfaces are merged.
• Corrects errors in importing Transfer files (introduced in 6.16).
• Corrects errors in SUM operators that have variable dependence and are referenced in equations.

 Version 6.16   04/15/11

• Implements new logic for locating arbitrary positions in the unstructured mesh.
• Removed redundant network license check accesses in some problems.
• Corrects some symbolic processing errors relating to divergence of tensors.
• Corrects a memory protection fault in moving mesh problems when all motions are exactly zero.
• Corrects an error in moving mesh problems in 2D cylindrical geometry.

 Version 6.15   12/13/10

• Corrects errors in boundary condition assignment in 2D-DXF import.
• Implements rotated ellipse in 2D-DXF import.
• Corrects occasional crash when requesting graphic printout.
• Corrects XCOMP(UNORMAL) and YCOMP(UNORMAL) in 2D.
• Forces PREFER_STABILITY selector in moving mesh problems.

 Version 6.14   09/09/10

• Corrects an error in the gridding of small ellipses.
• Increase common sub expression table size to reduce chances of overflow.
• Corrects an error in 1D CDF output.
• Automatically convert coordinate dependences to surrogate variable dependences in moving mesh problems.
• Corrects an occasional startup failure in moving mesh problems.
• Corrects an occasional infinite loop in 1D ELEVATION plots of moving meshes.
• Allows named POINTs to appear in parentheses (analogous to explicit points).
• Minor modification to mesh refinement logic.

 Version 6.13   05/31/10

• Diagnoses "New File" and "Save File" failure (typically file permission errors).
• Corrects treatment of dyadic vector product.
• Removes diagnostic report of empty equation in INACTIVE regions.
• Plot "ON REGION <number>" searches user's region numbers and defaults to sequential position if match is not found.
• Preserves node links for PERIODIC and CONTACT boundaries in TRANSFER MESH.
• Diagnose illegal power arguments in expressions (rather than deliver a runtime error).
• Expands tabs when printing scripts.
• Warn if TABULATE coordinates are decreasing.
• Convert MATRIX times scalar to scalar times MATRIX instead of rejecting expression.
• Corrects residual errors in treating Curl(scalar) in 2D.
• Corrects errors in TABLE output on ZOOM areas.
• Corrects tabulation of neighboring REGIONs for LIMITED FEATUREs on SURFACEs in 3D.
• Remove unsupported EMF format option from export dialog on Linux and Mac.
• Added PENWIDTH control to PLOT and SELECT sections.
• Corrects errors in "ON GRID" plots in time dependent problems.
• Implements TIMEMAX, TIMEMIN, TIMEMAX_T and TIMEMIN_T to find min and max values over time.
• Diagnoses common sub-expression table overflow (encountered only in extremely large, highly redundant arithmetic expressions).

 Version 6.12   02/07/10

• Restore interpretation of 2D Curl(scalar) to be consistent with earlier versions (lost in 6.10).
• Eliminate a busy wait in Pause dialog.
• Corrects occasional failure of initial value smoothing pass (SMOOTHINIT).
• Modify parser "Illegal Symbol" report to list all legal symbols.
• Corrects "Bad Matrix Reference" error when using coupled value boundary conditions on inactive variables.
• Corrects implementation of CONST ARRAYs reference in domain definitions.
• Random number generator is initialized only on file opening, not on each parse.
• Corrects indexing errors when using both CONTACT and INACTIVE controls.

 Version 6.11   12/15/09

• Corrects a memory leak associated primarily with vector plots.
• Corrects an assertion error when lose dongle (or network) and retry.
• Rotating a 3D mesh plot erroneously rotated all elevation plot locators.
• Implements 1/complex and CLOG(complex).
• Corrects errors in finding proper evaluation cells across thin domain gaps.
• Corrects an error in computing the block-inverse preconditioner in systems with symmetric coupling matrices.

 Version 6.10   11/10/09

• Corrects an error in evaluation of integrals involving parameterized definitions.
• Corrects an error in the export of time dependent Techplot files.
• Corrects the expansion of expressions containing the product of complex parameters and complex variables.
• Add facility to bypass automatic update checks.
• Additional plot error diagnostics.
• Diagnoses and rejects TABLEs with duplicated coordinate points.
• Improved error diagnostics in expression evaluation.
• Corrects an error in the processing of cascaded definitions (i.e. A=B=<expression>).
• Corrects an occasional error in ELEVATION plots on boundary curves in 3D.
• Corrects an error in handling of ARRAYs and MATRIXs loaded by element definitions, e.g. A=ARRAY[n], A[1]=1.

 Version 6.09   09/10/09

• Restores consistency with version 5 in the sign of ELEVATION plots of NORMAL on interior boundaries.
• Assures that boundary conditions on boundary paths will take precedence over boundary conditions on surfaces in 3D.
• Diagnoses bad region references in building 3D domains.
• Corrects errors in applying boundary conditions to INACTIVE variables.
• Support for display of version 3 plot files.
• Diagnoses mesh generation catastrophes due to near miss coordinates.
• Corrects the implementation of "STAGED (a BY b TO c)"
• Allow white space separators in STAGED lists (comma is now optional).
• Corrects errors in the implementation of CONTACT boundaries in 1D problems.
• Corrects an error (introduced in v6.04) that disabled the staging of ERRLIM.

 Version 6.08   07/01/09

• Added capability to communicate through a proxy server for update checks and internet key licensing. See the "Help | Web Proxy Settings" menu.
• Corrects and error in "Pause" control under Linux.
• Corrects diagnosis of 0/0 in evaluator.
• Corrects an indexing error in natural boundary conditions with sequenced equations.
• Update status panel at fixed time intervals (reduces panel flashing on fast problems.)
• Corrects application of boundary conditions to paths on specified surfaces in 3D.

 Version 6.07   05/25/09

• Corrects errors in memory usage report when scripts are re-run.
• Reports license features of network dongles, even when connected as local dongle.
• CONST ARRAY and CONST MATRIX store numbers rather than formulas. Allows generation of RANDOM arrays and matrices.
• Corrects an error in EXPORT of ELEVATION (array) with no VS qualifier.
• Implements "SELECT RANDOM_SEED=integer" to control random number generator.
• Sorts CRITICAL time list.
• Improved diagnostic for arithmetic errors in TIME_INTEGRALs.
• Defers printer connection to point of need, to avoid slow startup in systems with faulty printer specifications.
• Implements "SELECT DEBUG(GRID)" to aid in diagnosing mesh generation difficulties.
• Corrects an error that bypassed mesh density induction in closely spaced extrusion surfaces.
• Corrects an error in gridding 3D boundaries with sharp hidden breaks in surface slope.

 Version 6.06   04/16/09

• Added capability for XCOMP, YCOMP and ZCOMP to work with POINTs.
• EXPORT of MATRIX plot now uses matrix dimensions for table size.
• Corrects use of global MESH_SPACING and MESH_DENSITY controls.
• Corrects various errors in COMPLEX expression evaluation.
• Corrects errors in "View File" progress bar and hot keys.
• Corrects error in BATCH rerun.
• Corrects error in "Save As" of non-pde files.
• Corrects occasional crash on program close.

 Version 6.05   03/26/09

• Test for "disk full" errors while writing a PG6 output file.
• Added capability to stop the reading of a PG6 "view" file.
• Correct font sizes on some Linux platforms.
• Added capability for a CRITICAL time list.
• Added MODE_SUMMARY plot selector for compatibility with version 5 in eigenvalue problems.
• Corrects occasional errors in identifying duplicate plot domain specifications.
• Corrects occasional errors in locating positions in curved cells in 3D.
• Corrects occasional "Can't match prior cells" error.
• Corrects implementation of NATURAL boundary conditions in 1D Cylindrical and 1D Spherical models (area weighting factor had been omitted).

 Version 6.04   02/20/09

• Corrects an error in treatment of default error limit when ERRLIM is referenced but not defined.
• Corrects an occasional error in treatment of explicitly defined vectors in 2D problems.
• Corrects treatment of "New File" creation - new file is now displayed correctly.
• SUMMARY report for eigenvalue problems now sorts global and modal values.
• VIEW of graphic files now allows selection of plot time from a drop-down list.
• Corrects occasional crash in reporting errors on Linux platforms.

 Version 6.03   02/05/09

• Corrects an occasional error in SAVE operations with multiple threads.
• Adds capability for plotting CONTOURS and SURFACES on a deformed mesh.
• Adds labels for the second plot function in dual-contour plots.
• Abandons attempts to apply timestep controls to steady-state equations in time-dependent problems.   (Use SELECT SS_TIMECHECK to restore behavior of earlier versions.)

 Version 6.02   01/23/09

• Corrects an error in the -T command line switch for selecting default thread count.
• Modifies the logic of controlling matrix re-computation in nonlinear time-dependent problems, replaces the NRMATRIX switch with REMATRIX and restores version 5 switches PREFER_SPEED and PREFER_STABILITY.
• Corrects a threading error in SAVE and EVAL functions that caused data corruption with multiple threads.
• Corrects student-mode operation of the demonstration version.
• Corrects a memory protection fault when a plot mesh was empty.
• Corrects the import of version 5 transfer files.
• Corrects an error in the Jacobian matrix for variable dependence on integrals on imbedded features.
• Corrects occasional errors reading configuration and license files.
• Corrects an error that reset log file timestamps to zero after 24 hours of run time.

 Version 6.01   01/09/09

• Corrects and error in automatic update checking.
• Corrects an intermittent error in rewriting license file.
• Corrects an intermittent error in startup of time dependent problems with initial timestep much too large.

 Version 6.00   01/02/09

FlexPDE Version 6 is a major rewrite of the FlexPDE application.

Among the new features of FlexPDE version 6 in the initial release are:

• Multithreading - Support for dual and quad core processors. Run multiple problems simultaneously or use up to 4 threads for parallel execution within a single problem.
• Complex, Vector and Array Variables and Equations - Direct support of these data types simplifies equation construction.
• Regionally Inactive Variables - Variables can be declared inactive in some regions and active in others.
• Multiple Equation Sets - Splitting of equations into sets that are solved sequentially and alternately.
• Additional Status Graphs - Updated graphical interface to include plots of cell/node number, error, convergence and timestep.
• Internal Tabulation Facility - Build on-the-fly tables of computationaly intensive parameters for more economical execution.
• Arrays and Matrices - Extended support allows array and matrix operations for use in equations, graphics and domain construction.
• Planes, Cylinders, Spheres - Simplified Construction of Planes, Cylinders and Spheres in 3D.
• Stop and Restart Facility - Simplified facility for restarting a script after stopping.
• Web-based Licensing - Move license from machine to machine with web actions. No dongle to loose!