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Core Jep Java

• Introduction
• Basic Usage
• Variables
• Data types
• Operators
• Functions
• Custom Functions
• BigDecimal
• Modules
• FAQ
• Migration
• Version History

Advanced Features

• Manipulating Expressions
• Components
• Configurable Parser
• Serialization
• Threads
• Localization
• Grammar
• Other advanced features

Extensions

• Overview
• Type system and evaluation
• Fields
• Matrices
• Fast eval real
• Fast eval matrices
• Symbolic operations
• Expression cleaner
• Polynomials
• Rewrite expressions
• XJep Utilities
• Differentiation
• Other features
• Structured programming
• Lambda functions
• MathML conversion
• Statistical functions
• Version History

Extensions Version History

Version 2.1

New Lambda functions package

Add new package which allows anonymous lambda functions to be defined in expressions x=>x^2. The package adds higher order like map and fold which take lambda functions as arguments. It also adds a range operator [1..10] for easily specifying a range of numbers.

Bug fixes

• Fix bugs with POperator equalsPNode() and compareTo() methods, less critical as most expressions are represented as Polynomials and not POperators.
• Add equals() method to AbstractPNode so it is consistent with compareTo(). Add hashCode() methods for all subtypes.
• Fix bug with MrpEval when using expressions with more than 128 calls to binary functions which have non-scaler arguments. Now support up to 32767 separate vector arguments and 32767 separate matrix arguments.
• Add a RationalDivisionPrintRule which fixes bug with printing expressions with rational constants.
• MrpeEval.setVarVal(ref,double[]) can set scaler variable to arrays of length 1.
• Compare.process(Node node, Node children[]) now uses the children[] array rather than node.jjtGetChild(). This prevented any symbolic operations being applied before comparison.
• Fix bug with DimensionVisitor incorrectly calculated dimensions like id(2,3) where the output dimensions depend on constant arguments.

Breaking changes

• Dimensions class reworked to support vectors with 0 and 1 elements. Now a vector with 1 element is distinguished from a Scaler. The constant ONE and the method valueOf(int) are deprecated. The constant SCALER, EMPTY_VECTOR, ONE_ELEMENT_VECTOR should be used instead, and the methods valueOfVecOrScaler(int) and valueOfVec(int) remove ambiguity. The method valueOf(Dimensions,int) was buggy and is now fixed. String representation changed to distinguish scalers from vectors. The DoubleVector and GenericVector classes no allow zero length vectors. The MatrixList class turns empty lists into zero length vectors.

MrpeEval RpEval in multiple threads

MrpeEval now has facilities to make it easier to use in multiple threads. The getLightWeightInstance() returns a new instance which can be safely used for evaluation in multiple threads. This has copies of internal data so the evaluate(MrpCommandList) can be used with a given command list.

Instances created in this way lose information about Jep variable. Variable values can be accessed using the getVarValue(MrpVarRef ref) and the various setVarValue(MrpVarRef ref, double d) methods. But method using Jep Variable, i.e. updateFromJepVariables(), updateToJepVariables getVariable(MrpVarRef ref) getVarRef(String name) getVarRef(Variable var), do not work.

The instance also lose information about the matrix factory used to convert vector and matrix results. So the methods convertToVector(MrpRes res) convertToMatrix(MrpRes res) and convertResult(MrpRes res) don't work. But you can use the MrpRes.copyToVec(VectorI), MrpRes.copyToMat(MatrixI) and other methods of MrpRes.

A second method getLightWeightInstance(Jep jep) uses the Variable and MatrixFactory information from the new Jep instance. So the above methods are safe to use.

The RpEval class has similar methods. With and instance created using getLightWeightInstance() variable values can be accessed using getVarValue(int ref) and setVarValue(int ref, double val). When using getLightWeightInstance(Jep jep) references can be found using int getVarRef(Variable var) int getVarRef(String name).

Add a chargeFunctionName(String oldname, String newname) method to AbstractEval allowing alternative names for built in functions.

Add a String toString(RpCommandList coms1) to RpEval to print a more detailed version of a command list.

The RpEval, MrpEval, RpCommandList, MrpCommandList and related classes are all Serializable.

Other changes

General

• Rework OperatorTable and FunctionTable classes to mirror Jep 4.0 release with shallowCopy() methods.
• More consistency in constructors of PFMC's. With constructors with XJep arguments and also zero argument constructors with delayed initialisation.

com.singularsys.extensions.xjep

• Change Xjep.recursiveGetVarsInEquation() to return a sorted list rather than a set. Order will be in evaluation order.
• The TreeUtils class treats Integers and Complex numbers representing real integer values like double values with integer results. This allows correct simplification of expressions like x^(Complex(1,0)).
• Add Preprocess PFMC which causes the preprocessor to be run during evaluation.
• Add Eval PFMC which evaluates is argument during preprocessing.
• Fix handling of the XAssign.process() when the UseEquation flag is not set or the left hand side is a LValueI.
• Add new DirtyFunction interface for PFMC's which should not be cleaned when all arguments are constants. Add new DirtyRandom and DirtyThreadSafeRandom PFMC's which implement the interface. Modify ExpressionCleaner to respect interface.
• Add new XFunctionTable which uses the DirtyRandom PFMC.

com.singularsys.extensions.matrix

• Fix bug with GenericMatrix.equals(Object), which failed for two different matrices with equal elements. Now uses Arrays.deepEquals()
• Add some getters for components of MatrixComponents.
• Add the mean, sum, min, max functions from the com.singularsys.extensions.statistical package to MatrixFunctionTable.
• Add several convenience method to DimensionVisitor: visit(XVariable var) calculates the dimensions of a variable specified by an equation, getDimensions(Variable var) and getDimensions(Node node) find dimensions of existing objects which have already been calculated, and calcVariableDimensionsByValue(Variable var) calculates its dimensions using its value.
• The MatrixFactoryI now has a default method VectorI zeroVec(Dimensions dim) to create a vector of a given size.
• The MatrixFactory and MatrixField classes now all return this from the getLightWeightInstance() method.s
• LightWeight instances of all MatrixFactories and Fields return this.
• All the concrete Matrix and Vector types are Serializable. Base interfaces MatrixI, vectorI are not Serializable.

com.singularsys.extensions.matrixdiff

• Add some getters to reveal components of MDjep.
• Fix the DDimensionVisitor to work with variables with equations and some edge cases.

com.singularsys.extensions.fastmatrix

• MrpEval has new constructor MrpEval(Jep jep) which use a MatrixI factory taken from a Jep component.
• MrpEval has methods getLightWeightInstance(Jep newjep) which creates a thread safe copy using supplied Jep context.
• MrpeEval.setVarVal(ref,double[]) can set scaler variable to arrays of length 1.
• MrpeEval.evaluate() now throws an EvaluationException if the a PFMC called throws an Exception.
• MrpRes and subclasses have a toFlatternedArray() method which always returns a one dimensional array.
• MrpRes methods copyToVec(VectorI vec) and copyToMat(MatrixI res) now return the supplied VectorI or MatrixI respectively.
• MrpCommandList has a new MrpCommand getCommand(int i) method.
• Reduce visibility of some methods of internal classes of fastmatrix package.

com.singularsys.extensions.fastreal

• RpEval and RpCommandList can both be serialised.
• New updateFromJepVariables() methods to set variable values from the Jep instance.

com.singularsys.extensions.statistical

• Statistical functions now implement MatrixFunctionI so work with the Matrix package.
• Add a Range operation to the ElementMinMax
• For Mode add handling of cases where mode is not defined, returning NaN by default.
• Add a base class for the Ranks and SortElements functions.

com.singularsys.extensions.djep

• DJep has new methods replacePartialDerivativeByExpressions(Node), differentiate(DVariable var,String... names).

com.singularsys.extensions.rewrite

• Allow RewriteVisitor to transform constant and variable nodes. Creates new interfaces ConstantRuleI and VariableRuleI for rules which perform these actions.
• Add SmallNumberRule a constant rule which replaces small number with 0.0, useful for cleaning nodes.
• Add VariableShifter which replaces a variable "x" by a shifted version e.g. "x+5"

com.singularsys.extensions.polynomial

• Allow SymbolicEquals PFMC.
• Fix bug in Compare PFMC.
• All types of PNodeI are serializable.
• PolynomialCreator respects the DirtyFunction interface.

Version 2.0 (released 2018/07/05)

Major re-release to match the Jep 3.5 release.

All packages moved to the com.singularsys.extensions and reworked to use the Jep 3 framework.

New packages

• Field com.singularsys.extensions.field
• Matrix com.singularsys.extensions.matrix
• MathML com.singularsys.extensions.mathml
• Structured programming com.singularsys.extensions.structure

Renamed

• fastreal org.lsmp.djep.rpe renamed to com.singularsys.extensions.fastreal
• fastmatrix org.lsmp.djep.mrpe renamed to com.singularsys.extensions.fastmatrix
• polynomials org.lsmp.djep.sjep renamed to com.singularsys.extensions.polynomials

Incorporated in main jep release

• Printing: equations can be easily printed or converted to strings with intelligent handling of brackets.
• re-entrant parser
• Utilities for examining and modifying the parse trees

Removed

• groupJep replaced by Field package com.singularsys.extensions.field
• matrixJep and vectorJep replaced by Matrix package com.singularsys.extensions.matrix

In development

• Date and time functions.
• Summation type functions.

Version 1.1.1 (released 2007/04/25)

• Fixed bug [ 1567116 ] VectorJep division

Version 1.1.0

New Features

• Simplification: A new package org.lsmp.djep.sjep has a more advanced simplification algorithm. This will collect terms with the same powers so 3x+x^2+4x+x^2 is transformed to 7x+2x^2. Full expansion of polynomials is also available so (1+x)^3 it transformed to 1+3x+3x^2+x^3.
• Fast Evaluation: Two new classes in the org.lsmp.djep.rpe package peform faster evaluation over the reals. The speed up can be between four and ten times faster. One of the classes RpEval works with singled valued functions and the other MRpEval works with vectors and matrices optimised for 2,3, and four dimensions.
• New Functions: Several new functions have been added, including standard vector and matrix operations and wrappers around the JAMA matrix algorithms which can solve matrix equations.

Minor Improvments

• Evaluator now swithchable to allow null variable values.
• SymbolTable can now tell java.util.observers when new variables are created.
• Reworked Console aplications to make them easily extendable.
• Rewrite Visitor can allow arbitary term rewriting rules.
• XJep has methods to find the variables in an equation.

Version 2.3.0 release (renamed to DJEP 1.0.0)

No major changes were made for the release.

Version 2.3.0 beta 1 - 12 April 2004 (formerly known as 2.3.2 beta)

This version now has a stable API an should be used in preference to earlier versions.

Main changes since 2.3.0a:

• Added a groupJep package: this allows calculation over arbitrary groups like the rational numbers.
• Changed the org.nfunk.jep.values.Complex to extend number, modified all postfix math commands to suit.
• Changed the Scaler, MVector and Matrix types to extend number.
• Added features for a re-enterant parser.
• Major re-nameing of packages and classes. Removed unnecessary classes.
• Documentation updated.
• The ^ operator is now overloaded to be the cross product for 3D vectors as well as power.
• Parser is now switchable for whether . can appear in an identifier x.y can either be a single variable (default for Jep, XJep and DJep) or as the dot product x . y (default for VectorJep and MatrixJep).
• New functions if, str, complex, polar.
• Several other minor changes.

Features yet to come

A few new functions to be added, min, max, sgn, differentiation for if.
Vector and matrix functions: det, inverse, transpose ....
Faster evaluation, possibly based of a reverse polish type of evaluation scheme, eliminating as much object creation as possible.
Various conversion routines to other formats MathML etc.

Version 2.3.0 alpha - 28 Feb 2004 (formerly known as 2.3.1 alpha)

This is the third release of the package, released 28/Feb/04. I'm really just rushing this out as some people have been asking for documentation which is included here. Still more documentation to come. Also the code is still in a fairly mutable state and I still expect to move some things around so don't expect the the API to be stable. Hopefully it will just be the inner workings which change the main interface for users is nearly fixed. The most important changes in this package are

• Renames org.lsmp.djep.matrixJep.MatrixDJep to org.lsmp.djep.matrixJep.MatrixDJep.
• Moved the console applications to their own package
• Added some more examples
• Added some documentation
• Added some JUnit test
• Rationalised some of inner workings and cleaned up some unnecessary stuff, notably in relation to variables and their evaluation.

Version 2.3.0a - Jan 04

First release as an official part of JEP.

Added support for vectors and matrices.
Major reworking of differentiation, functionality now split into two packages org.lsmp.djep.xjep - printing, tree manipulation etc, and org.lsmp.djep.djep - differentiation.
Changed the org.nfunk.jep.SymbolTable class so the elements are now of type org.nfunk.jep.Variable rather than just its value. ASTVarNodes now refer to the variable object.
Several changes in exposed API for JEP.
Introduced an org.nfunk.jep.Operator and org.nfunk.jep.OperatorSet types which represent the basic +,-,*,/,etc operators. Eliminates the excess creation of one object for each instance of an operator.

Known bugs in version 2.3.0a

Several bugs are known in version 2.3.0a.

• Differential of "diff(a^x,x)" should be "a^x * ln(a)" but it's "a^x * ln(x)".
• Evaluation of "(x*x)*(x*x)" causes a ParseError in VectorJep and MatrixJep. Quick fix: edit org.lsmp.djep.vectorJep.function.MMultiply.java
  On line 72: in the run method, comment out the line

  if(stack.size()!=2) throw new ParseException("Multiply: should have two children its got "+stack.size());

• Matrix multiplication (i.e. matrix * matrix) does not work. Fix: upgrade to later version.
• vector * vector multiplication does not work.
• cannot combine results of matrix operations with functions ie. "sqrt([1,2].[1,2])" fails. Fix: upgrade.
• Dot and cross product cannot be differentiated.
• uminus is broken for MatrixJep.
• Problems repeated evaluation of sequences of equations.
  Quick fix: always uses before reevaluation. j.getSymbolTable().clearValues();
• Problems with using different types of JEP in the same application. They share a static Operator class which can have the wrong pfmc's for the type of JEP.

First release

The first release of the package was about September last year. It just included differentiation facilities. The package has had a major rework since then.