Revision history for Perl extension Math::Symbolic.

0.603  Wed Mar  4 18:21 2009
    - Fix regression in the Yapp-parser parser extension mechanism.

0.602  Tue Mar  3 17:05 2009
    - Fix RT #43783: Bug in the term simplification of constants in derivatives
      of differences. (Reported by Alexander Platt)

0.601  Thu Feb  5 21:50 2009
    - Support for object-private parser extensions via
      Math::SymbolicX::ParserExtensionFactory.

0.510  Sun Jan 27 20:05 2008
    - Implement commutativity information in @Math::Symbolic::Operator::Op_Types
      (used by Math::Symbolic::Custom::Pattern 2.00 and later).

0.509  Thu Dec 20 22:01 2007
    - Add new operator type: atan2 which mostly corresponds to perl's atan2.
      This provides some saftey during evaluation of atan(y/x) which may be
      more common than any other use the arc tangent.

0.508  Mon May 28 17:40 2007
    - Fix two bugs in simplification (James Mastros).
    - Some simplification improvements. (It's still crude, though.)
    - Add mod_add_constant and mod_multiply_constant to DefaultMods.

0.507  Sat Jan 20 11:35 2007
    - The Yapp parser was improved so that it now works with
      Math::Symbolic::Custom::Transformation.

0.506  Fri Jan 12 11:35 2007
    - Much more tests.
    - Added test_num_equiv to DefaultTests for testing approximate equivalence
      of a M::S tree and another or a M::S tree and a sub.
    - Added a 'sqrt' function to both parsers which is transformed into
      '(...)^0.5' internally.
    - The Yapp parser now works with Math::SymbolicX::ParserExtensionFactory!

0.505  Fri Jan 12 11:35 2007
    - Fixed bug in ::Parser related to missing precompiled parsers.
      (Thanks, Jerrad Pierce)
    - You can now request a Parse::Yapp-based parser from the ::Parser->new()
      method.
    - Add is_one, is_zero, is_zero_or_one to DefaultTests
    - Now does some simplification while deriving.
    - Fix bug while deriving some logarithms.
    - More derivative tests.

0.504  Fri Nov  3 16:15 2006
    - Improved POD coverage tests.
    - This release is mainly intended to fix some PAUSE indexing trouble
      of the last release.

0.503  Fri Sep 12 18:08 2006
    - Added an "exp()" function to the parsers. So now you can use "exp()" in
      expressions and have it transformed to "e^(...)" internally with a pretty
      high-precision Euler number. (The one returned by M::S::Constant->euler())

0.502  Fri Apr 28  9:20 2006
	- Small changes to the new parser to make it indexable by PAUSE.
	- Added a script to compile the Yapp parser.
	- Removed the Yapp parser's readme because the script documents itself.

0.501  Thu Apr 27 19:19 2006
	- Added a completely new and optional(!) parser as
	  Math::Symbolic::Parser::Yapp.
	  This new parser should be about 30x faster and it's over 10x faster in
	  all benchmarks.
	- Documented the new parser in Math::Symbolic::Parser.
	- Augmented the tests.
	- Added the new parser's grammar as Yapp.yp.
	
0.201  Tue Feb 14 15:32 2006
	- Rewrote the to_latex() LaTeX dumper. Since it's quite a bit of code
	  which few people actually need to load, the LaTeX dumper will be
	  availlable as a separate distribution
	  Math::Symbolic::Custom::LaTeXDumper.
	- Ergo: Removed to_latex() from Math::Symbolic::Custom::DefaultDumpers.
	- For some, this might be a change that breaks backwards compatibility.
	  All you would need to do when upgrading Math::Symbolic is
	  installing the aforementioned distribution and adding a call
	  'use Math::Symbolic::Custom::LaTeXDumper;' to your program and the new,
	  shiny *much* improved to_latex() method will be availlable.
	- Don't blame me! to_latex() was flagged as 'extremely experimental'!

0.164  Sat Dec 31 09:57:20 2005
	- Fixed bug in det() of ::MiscAlgebra. Thanks to Markus Laire who
	  noticed it.
	- Added better tests to test for det() on 4x4 matrices and larger.

0.163  Thu Oct 06 21:43:59 2005
	- Added 'use strict;' to the top of ::Parser::Precompiled.
	- Added 'use strict;' to the parser generator.
	- Changed build process to use Module::Build but still supports
	  Makefile.PL.

0.162  Thu Sep 22 22:19:41 2005
	- Added t/00pod.t which runs Test::Pod if it is availlable.
	- Added a "license" line to META.yml

0.161  Wed Sep  7 21:04:02 2005
	- Corrected a few bugs in ::Derivative.
	- Sped up ::Derivative a bit.
	- Included obvious simplifications into the derivative
	  routines that avoid crap such as '0*foo'.
	- Small modifications to t/04deep_derivatives.t.
	  We derive only ten times instead of twenty.
	- simplify() now takes an argument: A boolean indicating
	  whether or not the routine has to clone.
	- Fixed bugs in simplify().
	- Improved the simplification routines.

0.160  Wed Aug 17 21:16:46 2005
	- Fixed a bug in the parser that prevented it from parsing C
	  floating point numbers of the form 1e10.
	- Hacked on the parser so it's now at least 50% faster!
	  This results in a very noticeably speedup. Test times jumped
	  from 17 seconds to 12 seconds on my machine.

0.150  Tue Aug 02 22:48:56 2005
	- Optimized a couple of bits in the module. This should help a
	  very slight bit with performance.
	- Nothing that warrants the jump in version number. The jump is meant
	  to signal that you should upgrade if you haven't already. Anything
	  prior to 0.135 may become a problem due to ::Precompiled.

0.136  Sat Jul 30 23:27:03 2005
	- Added a (long) paragraph about performance to Math::Symbolic docs.
	- Cleaned the README from some old cruft. (Who cares what was introduced
	  in version 0.110? Read the change log. Oh. Well, that's what you're
	  doing right now!)

0.135  Fri Jul 29 21:23:36 2005
	- Math::Symbolic is over 2 years old now.
	- It's been 1 year since the last released version.
	- Fixed bugs in Math::Symbolic::Parser::Precompiled that might cause it
	  to not compile on some systems. Probably due to different behaviour of
	  Parse::RecDescent in different versions or so.
	- Sped up t/18vectorcalc.t which is, well, still slow, but it now has
	  some Data::Dumper dumped code in its DATA section. That's because Perl
	  parses *much* faster than Parse::RecDescent!
	- Doctored around a bit on the docs.

0.134  Thu Jul 29 17:51:53 2004
	- Corrected embarassing derivative bug.
	- Modified value() and apply() behaviour. Should not break
	  compatibility but increase speed.
	- Constants that are created with an undefined value now
	  throw a fatal error. Previous behaviour was to do so on value()
	  calls which turned out to be hard to debug.
	  This may break compatibility in bad code.
	- Tests for the above.

0.133  Mon May 10 10:12:44 2004
	- Documentation fixes.
	- Parser returns undef if the input text hasn't been consumed
	  entirely now.
	- Fixed bug in 16tests.t (test 22).
	- Added test for the above behaviour.

0.132  Mon Apr 12 18:02:27 2004
	- Added additional syntax to value() and set_value() methods
	  as suggested by Henrik Edlund.
	- Fixed bug in precompile_grammar.pl that broke the precompiled
	  parser on many systems.
	- Fixed bug in Math::Symbolic::Compiler that caused exports to fail.
	- Reworked some of the examples. Particularily added an example that
	  graphically demonstrates the differences between different Taylor
	  polynomials. (examples/run16.pl)
	- Changed the overloaded interface: If you add or subtract an
	  existing Math::Symbolic object to/from <undef>, the result will be
	  the Math::Symbolic::* object. (in case of the subtraction, the result
	  will be a unary minus and the Math::Symbolic::* object.)
	  Example where this is very useful:
	  my @objects = (...some objects...);
	  my $sum;
	  $sum += $_ foreach @objects;

0.131  Wed Mar 31 14:55:13 2004
	- Changed $VERSION = 0.xxx; to ...= '0.xxx'; since that broke
	  the Test::Distribution version tests.
	- Improved documentation for M::S::MiscAlgebra.
	- Added linear_solve to M::S::MiscAlgebra.
	- Added docs and tests.
	- Fixed errors in the documentation for M::S::Compiler.
	- Extra tests for the compiler.
	- Added the explicit_signature() method.
	- Added tests and documentation.
	- Fixed nasty bug in the compiler.
	- Fixed even nastier misdocumentation of the compiler.
	- Thanks to Henrik Edlund's input, one can now pass a hash ref to
	  the compile* functions instead of an array ref.

0.130  Sun Feb 15 23:54:54 2004
	- Fixed documentation bug in M::S::VectorCalculus.
	- Increased the accuracy of pi and euler number.
	- Fixed documentation bug in M::S::Derivative
	- Removed Pod::Coverage from the Makefile.PL requirements
	- Modified the 00sanity.t tests to only use Pod::Coverage when
	  availlable.
	- Removed 1 test from 20miscalgebra.t which took way too long on
	  automatted test platforms.
	- Renamed 00sanity.t to 00podcover.t and added 00dist.t which uses
	  Test::Distribution for well, exactly that.
	- Modified precompile_grammar.pl (CVS only) to include a $VERSION
	  in M::S::P::Precompiled.

0.129  Sat Feb  7 19:04:50 2004
	- Fixed associativity bug in parser for exponentiation.
	- Regenerated the Precompiled Parser.
	- Improved simplification of sums and differences.
	- Removed some tests that tested methods redundantly with too much
	  data. These tests unduly slowed down testing to the point that
	  automatted testing facilities considered the tests failed.

0.128  Wed Feb  4 13:14:12 2004
	- Fixed bug in Constant.pm about special tag not being unset when
	  the value of the constant is changed.
	- Documented an important gotcha with the replace() method in Base.pm
	- Added an extra check to the apply() method in Operator.pm that
	  makes sure no "undefined ... in [arithmetic operation]" errors are
	  generated when computing 1/0.

0.127  Sat Jan  3 19:20:29 2004
	- Happy New Year!
	- There was an error in the 0.126 distribution related to
	  the Math::Symbolic::Parser::Precompiled module.

0.126  Sun Nov  9 16:54:26 2003
	- Fixed parser bug with asinh, acosh.
	- Added Oliver Ebenhoeh to the list of contributors.
	- Now including a precompiled Parse::RecDescent grammar
	  as Math::Symbolic::Parser::Precompiled. That's for startup
	  performance.

0.125  Wed Oct  8 16:19:13 2003
	- Implemented binomial_coeff in AuxFunctions.
	- Now requiring Memoize to be installed.
	- Added META.yml and Makefile.PL dependency.
	- Added bell_number() to AuxFunctions.
	- Added bell_polynomial to MiscAlgebra.
	- Slightly improved simplification.

0.124  Wed Oct  1 15:08:49 2003
	- Now value() and apply() return undef if any var is undefined.
	- Docs for the above.
	- value() on constants that aren't defined die.
	- Fixed some documentation oversights.
	- Added to_code, to_sub to DefaultDumpers.
	- Added fill_in_vars() to Base.
	- Moved the run*.pl files to ./examples/
	- Added the perltidy.conf that is being used with this module
	  to the CVS development tree.
	- Added WronskyDet to VectorCalc
	- Modified MANIFEST.skip to ignore CVS dirs and perltidy.conf
	- Added 00sanity.t which uses all modules and uses
	  Pod::Coverage to test for validity of documentation.
	- Added requirement of Pod::Coverage to META.yml and Makefile.PL

0.123  Fri Sep 26 00:49:55 2003
	- Fixed the previously slightly broken to_latex() method.
	- Added support for automatic greek output for to_latex().
	- Added custom variable mapping for to_latex().

0.122  Tue Sep 23 22:18:19 2003
	- Added the 'to_' delegation prefix.
	- Added Math::Symbolic::Custom::DefaultDumpers.
	- Added support for dumping to LaTeX! *evil grin*

0.121  Sun Sep 14 14:41:31 2003
	- Added M::S::MiscAlgebra and the det() routine.
	- Slightly improved simlification process
	- Added is_identical_base to the DefaultTests
	- Started implementation of mod_join_simple in DefaultMods.

0.120  Thu Sep 11 16:42:51 2003
	- Now mentioning "Hesse" as exportable function of M::S::VectorCalclus.
	- Implemented TotalDifferential and DirectionalDerivative.
	- Implemented TaylorPolyTwoDim.
	- Cross-referenced the two taylor-related function docs.
	- Tests and documentation for the new features.
	- Added run17.pl to the distribution.

0.119  Wed Sep 10 00:48:02 2003
	- Improved exponentiation simplification.
	- Now surpressing deep recursion warnings.
	- Fixed a few bugs in the tree descending routines.
	- Introduced M::S::MiscCalculus with TaylorPolynomial,
	  TaylorErrorLagrange, and TaylorErrorCauchy.
	- Added run16.pl to the distribution.
	- Referenced the new module in Math::Symbolic.
	- Added tests.

0.118  Tue Sep  9 13:18:24 2003
	- No more requiring Parse::RecDescent via Makefile.PL.
	  After all, you can use Math::Symbolic without the parser
	  (though you sacrifice the best piece of the interface
	  that way.)
	- Updated META.yml to recommend Parse::RecDescent and require it
	  for building.
	- Added Hesse() to M::S::VectorCalculus.
	- Amended tests for M::S::VectorCalculus.
	- Fixed typo in AUTHORS sections
	- is_identical now auto-parses first argument if not a M::S tree.
	- Slightly improved the simplification process using is_identical.
	- Fixed various small bugs in M::S::Constant and M::S::Operator.
	- Fixed parser bugs related to unary minus.
	- Improved unary minus simplification.
	- Added more unary minus parsing/simplification tests.

0.117  Mon Sep  8 17:12:36 2003
	- Added M::S::VectorCalculus with rot, grad, div, Jacobi
	- Referenced it in the docs to the main module.
	- Added run15.pl example of usage.
	- Added tests.
	- Fixed bug in M::S::Variable

0.116  Wed Sep  3 22:16:51 2003
	- Added META.yml
	- Removed "Exporter" dependency in Makefile.PL. Who needs to install
	  Exporter from CPAN anyway?
	- Added run14.pl with Math::Complex stuff.
	- Math::Symbolic::Parser now defers loading Parse::RecDescent to the
	  first call of the parser constructor.
	- Math::Symbolic now defers creating a parser to the first call of
	  "parse_from_string".
	- Together, the above changes made the testsuite run 30% faster
	  because many of the basic test scripts don't use the parser.

0.115  Tue Sep  2 16:23:15 2003
	- Moved to sf.net
	- Ran perltidy over the distro.
	- Lots of doc patches including a section on extending the module.
	- Added can() overriding to Base.pm in order to reflect method
	  delegation.

0.114  Thu Aug 28 13:26:47 2003
	- Fixed bug in set_value() routine that was introduced in 0.113.
	- New example in Math::Symbolic docs

0.113  Sun Aug 17 19:13:28 2003
	- Added the MS::Constant pi() constructor
	- Added tests and docs.
	- Added the MS::Base descend() routine. (This is a biggie.)
	- Converted as many descending routines as possible to be using
	  descend() instead of descending themselves.
	  These include is_constant, is_simple_constant, is_sum,
	  apply_constant_fold, apply_derivatives()
	- Added new method namespace to be delegated to M::S::Custom:
	  'contains_.
	- Added docs and tests.
	- Added replace().
	- Fixed a bug in implement(). Now also autoparses strings.
	- Added is_identical() to M::S::C::Default
	- Split up M::S::C::Default into M::S::C::DefaultTests and
	  M::S::C::DefaultMods.
	- Added the M::S::Base::descending_operands() routine that tries to
	  find the most sensible operands to descend into.
	- Added the operand_finder parameter to descend().
	- Moved set_value to M::S::Base and refactored it to use descend().
	- Modified implement() similarily to set_value.
	- Fixed some bugs in implement(), too.
	- Hacked simplify() some more. This needs to be cleaned up real soon.

0.112  Thu Aug  7 19:11:38 2003
	- Continued moving functionality into the M::S::Custom::* namespace.
	- Moved constant_fold into custom namespace
	- Added tests.
	- Fixed serious bugs.

0.111  Tue Jul 29 12:38:40 2003
	- Added Math::Symbolic::Custom::*.
	- Added custom transformation and test functionality.
	- Added is_sum(), is_constant(), is_integer() to M::S::C::Default
	- Added documentation and tests for the above.
	- Moved apply_derivatives() to the MSC::Default namespace.
	- TODO goals met with this release:
		+ Create a Math::Symbolic::Custom class and a
		  Math::Symbolic::Custom::Default class.
		+ The Math::Symbolic::Custom::Default class is to
		  contain all builtin simplification and term-transformation
		  routines.
		  (Also contains methods that tests trees for particular
		  properties)
		+ All calls to Math::Symbolic methods that cannot be
		  resolved in the Math::Symbolic inheritance hierarchy
		  (which should consist of the package itself, anyhow) and
		  that start with "apply_" should be delegated to the subs
		  named apply_... in the Math::Symbolic::Custom
		  package.
		  ('is_', 'test_', and 'mod_' also delegated.)
		+ Math::Symbolic::Custom should load
		  Math::Symbolic::Custom::Default.
		+ Math::Symbolic::Custom::Default should inherit
		  from a package named Math::Symbolic::Custom::Base
		  which defines a special import routine that automatically
		  adds the loaded module to the @ISA of
		  Math::Symbolic::Custom.
		  (Implemented this using a custom exporter scheme.)
		+ Thus, users can extend the number of
		  Math::Symbolic::Custom's by writing a package with
		  transformation subroutines in it that just inherits
		  from Math::Symbolic::Custom::Base. Upon use-ing the
		  custom module, the routines will automatically be
		  added to Math::Symbolic's transformation and testing
		  repertoire.

0.110  Sat Jul 19 15:16:11 2003
	- Documentation patches.
	- Added total derivatives.
	- Fixed the host of bugs that were discovered while implementing
	  total derivatives.
	- Added tests.
	- Added docs.
	- Added docs section on variable passing styles to Compiler.pm
	- Added implement()
	- Fixed uncovered bugs in total derivatives.
	- TODO goals met with this release:
		+ Add signatures to variables.
		+ Add signature() methods to all elements.
		+ Amend parser to parse signatures.
		+ Given the signature-parser enhancements, total derivatives
		  start making sense.
		  Since function signatures must be defined by their signatures
	 	  when they're used, total derivatives can be applied to all
		  functions. (Or, if their implementation is still undefined,
		  they can possibly still be kicked out because of their
		  non-dependence on a particular variable.)
		+ Add tests for sigs.
		+ Add tests for the new features.

0.109  Fri Jul 18 00:34:00 2003
	- Documentation patches.
	- Added signature attribute to variables.
	- Added signature() method to all tree elements.
	- Added set_signature() method to variables.
	- Some docs for the sig. changes.
	- Tests for the sig. changes.
	- Modified parser to parse unknown 'function(list)' constructs
	  as variables and their signatures.
	- Tests for the parser changes.
	- Documentation for the parser changes.
	- Added some bad examples to the parser man-page.

0.108  Wed Jul 16 22:41:01 2003
	- Added Math::Symbolic::Compiler (as a modified to_sub.pl).
	- Modified value() semantics to optionally take arguments.
	- Added set_value() method.
	- Added lots of docs.
	- Added some tests.
	- TODO milestones met with this release:
		+ Refactor the to_sub.pl code to a package that allows to
		  compile Math::Symbolic trees to subroutines and/or code.

0.107  Sun Jul 13 21:25:29 2003
	- Fixed tests. (Note to self: recreate MANIFEST for dists.)

0.106  Sun Jul 13 19:56:29 2003
	- Modified the parser to parse unknown identifiers as variables.
	- Modified Operator constructor to send operands through the parser
	  if they aren't valid Math::Symbolic::* objects.
	- Added and fixed docs. A lot.
	- Added tests.

0.105  Wed Jul  9 18:56:33 2003
	- Added several important items to the TODO.
	- Accepted the fact that the TODO is growing faster than the code base.
	- TODO milestones met with this release:
		+ Add reasonable overloaded interface for arithmetic
		  operators and some mathematical functions as far as feasible.
		+ Overloaded interface for exp, sqrt, log, +,-,*,/,**.
		+ Overloaded interface for boolean context and stringification.
		+ O. i. for unary minus
		+ O. i. for trig functions
		+ Overloaded interface for numerical context.
		+ Tests for the above.
		+ Documentation for the above changes

0.104  Sat Jul  5 19:17:00 2003
	- Added to_sub.pl to the distribution. (Math::Symbolic -> Perl sub
	  compiler.) This is just a proof-of-concept.

0.103  Thu Jun  26 15:08:12 2003
	- Fixed test errors.
	- Added (very little) documentation.

0.102  Wed Jun  25 21:04:41 2003
	- Added overloaded interface for arithmetic operators, exp, log,
	  sqrt, boolean context, numerical context, sin, cos, mutators.
	- Added tests.
	- Added docs.

0.101  Fri Jun  20 15:45:10 2003
	- Documentation fixes

0.100  Fri Jun  20 01:32:32 2003
	(Yep, I hack at random hours.)
	- Implemented hyperbolic sine, h cosine.
	- Implemented partial derivatives for h sine, h cosine
	- Amended parser for h sine, h cosine.
	- Same for tangents
	- Myriad of bugfixes
	- ExportConstants now includes (and exports) PI and EULER constants.
	- Renamed class data in M::S::Operator.
	- Cotangent.
	- Arc sine, arc cosine, arc tangent, arc cotangent.
	- Hyperbolic area sine, h. a. cosine
	- Tests for the above.
	- Broke the parser badly.
	- (much later) Fixed it again.
	- Some more documentation
	- Renamed test files
	- TODO milestones met with this release:
		+ Add sine/cosine
		+ Amend parser to parse sine/cosine.
		+ Add sinh/cosh or at least allow the user to use them in the
		  input string to the parser and have them replaced with
		  (e^x ± e^-x)/2
		+ Amend parser to parse hyperbolic sine/h. cosine.
		+ Add tan, arctan, arcsine, arccosine
		+ Amend parser to parse tan / arctan, arcsine / arccosine.
		+ Find a more reasonable naming scheme for class data and
		  rename appropriately.
		+ Add tests for the new features.

0.090  Wed Jun  18 16:37:56 2003
	- Implemented sine, cosine, sine/cosine derivatives
	- Amended parser for sine and cosine functions

0.080  Sun Jun  15 22:17:11 2003
	- Parser now a module (M::S::Parser)
	- Parser accessible through new_from_string().

0.070  Sat Jun  14 18:21:47 2003
	- Parser now outputs Math::Symbolic tree
	- Fixed unary-minus to infix issues.

0.060  Wed Jun  11 16:58:59 2003
	- Now including rudimentary parser for algebraic expressions.
	- Some documentation added.

0.050  Fri Jun  6 16:57:19 2003
	- Moved the rules for partial derivatives to separate
	  subs and introduced a lookup-table.

0.040  Thu Jun  5 01:12:23 2003
	- Many changes again.

0.030  Wed Jun  4 18:43:00 2003
	- More major enhancements (exp function, log, derivative as operator)

0.020  Wed Jun  4 14:29:15 2003
	- First working version.

0.010  Tue Jun  3 21:45:57 2003
	- original version; created by h2xs 1.21 with options
		-AX Math::Symbolic

