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JEP is a Java library for parsing and evaluating mathematical expressions.
/* @author rich
* Created on 26-Feb-2004
*/
package org.lsmp.djepExamples;
import org.nfunk.jep.*;
import org.lsmp.djep.vectorJep.*;
/**
* Examples using vectors and matricies
*/
public class VectorExample {
static VectorJep j;
public static void main(String args[]) {
j = new VectorJep();
j.addStandardConstants();
j.addStandardFunctions();
j.addComplex();
j.setAllowUndeclared(true);
j.setImplicitMul(true);
j.setAllowAssignment(true);
// parse and evaluate each equation in turn
doStuff("[1,2,3]"); // Value: [1.0,2.0,3.0]
doStuff("[1,2,3].[4,5,6]"); // Value: 32.0
doStuff("[1,2,3]^^[4,5,6]"); // Value: [-3.0,6.0,-3.0]
doStuff("[1,2,3]+[4,5,6]"); // Value: [5.0,7.0,9.0]
doStuff("[[1,2],[3,4]]"); // Value: [[1.0,2.0],[3.0,4.0]]
doStuff("[[1,2],[3,4]]*[1,0]"); // Value: [1.0,3.0]
doStuff("[1,0]*[[1,2],[3,4]]"); // Value: [1.0,2.0]
doStuff("[[1,2],[3,4]]*[[1,2],[3,4]]"); // Value: [[7.0,10.0],[15.0,22.0]]
doStuff("x=[1,2,3]"); // Value: [1.0,2.0,3.0]
doStuff("x+x"); // Value: [2.0,4.0,6.0]
doStuff("x.x"); // Value: 14.0
doStuff("x^x"); // Value: [0.0,0.0,0.0]
doStuff("ele(x,2)"); // Value: 2.0
doStuff("y=[[1,2],[3,4]]"); // Value: [[1.0,2.0],[3.0,4.0]]
doStuff("y * y"); // Value: [[7.0,10.0],[15.0,22.0]]
doStuff("ele(y,[1,2])"); // Value: 2.0
}
public static void doStuff(String str) {
try {
Node node = j.parse(str);
Object value = j.evaluate(node);
System.out.println(str + "\tvalue " + value.toString());
}
catch(ParseException e) { System.out.println("Parse error "+e.getMessage()); }
catch(Exception e) { System.out.println("evaluation error "+e.getMessage()); e.printStackTrace(); }
}
}