Z Evaluation Engine

Z Evaluation Engine (ZEE) is a Java library for parsing and evaluating sets of equations.

Notable capabilities of the engine include:

• User-define arbitrary functions and variables
• Supports all standard java.lang.Math functions and constants, plus additional functions
• Allows Analytic, Piecewise, and Numeric (interpolated) function definitions

Building

gradle clean build

this command will build the javadocs and run the code coverage report all sources and javadocs will be bundled in the final build artifact

to install to local repository as a maven artifact, use gradle clean install

Usage

ZEE allows you to do everything from define and evaluate simple expressions and variables, to define sets of functions and evaluate them together over the domain of your choice.

// simple expression evaluation
String toParse = "log10(1000) / (1.4 + 1.6)";
double result = EquationProcessor.evaluateExpression(toParse);
System.out.println(result);      // writes out "1.0"

// simple expression with variables
Map<String, String> variables = new HashMap<String, String>() {{ put("a","2"); }};
EquationProcessor k = new EquationProcessor(variables);
System.out.println(k.evaluate("2 + a"));      // writes "4"

// define a set of functions
Map<String,String> eqs = new HashMap<String,String>();
eqs.put("piApprox(k)","8*cumsum(ChebyshevTerm(k))");
eqs.put("ChebyshevTerm(k)","( (-1)^k * (sqrt(2)-1)^(2*k+1)) / (2*k+1)");
eqs.put("absError(k)", "abs(pi-piApprox)");
EquationProcessor k = new EquationProcessor(eqs);

// define the domain variable and its values to evaluate
Map<String,String> defs = new HashMap<String,String>();
defs.put("k","[0:20]");

// evaluate the complete function set over the domain, outputting the functions that you want
List<String> cols = Arrays.asList("k", "ChebyshevTerm", "piApprox", "absError");
List<double[]> output = k.evaluate(defs,cols);

For a complete set of examples, see "sample" package in the unit tests, and the examples project.