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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.matrixJep.*;
import org.lsmp.djep.mrpe.MRpCommandList;
import org.lsmp.djep.mrpe.MRpEval;
import org.lsmp.djep.mrpe.MRpRes;
import org.lsmp.djep.vectorJep.values.*;
/**
* Examples using fast reverse polish calculator with vectors and matrices
*/
public class MRpExample {
static MatrixJep mj;
static MRpEval rpe;
public static void main(String args[]) {
mj = new MatrixJep();
mj.addStandardConstants();
mj.addStandardFunctions();
mj.addComplex();
mj.setAllowUndeclared(true);
mj.setImplicitMul(true);
mj.setAllowAssignment(true);
rpe = new MRpEval(mj);
// 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]]
// vectors and matrices can be used with assignment
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("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]]
// accessing the elements on an array or vector
// doStuff("ele(x,2)"); // Value: 2.0
// doStuff("ele(y,[1,2])"); // Value: 2.0
// using differentation
// doStuff("x=2"); // 2.0
// doStuff("y=[x^3,x^2,x]"); // [8.0,4.0,2.0]
// doStuff("z=diff(y,x)"); // [12.0,4.0,1.0]
// doStuff("diff([x^3,x^2,x],x)");
// System.out.println("dim(z) "+((MatrixVariableI) mj.getVar("z")).getDimensions());
}
public static void doStuff(String str) {
try {
Node node = mj.parse(str);
Node proc = mj.preprocess(node);
Node simp = mj.simplify(proc);
MRpCommandList list = rpe.compile(simp);
MRpRes res = rpe.evaluate(list);
mj.print(node);
// conversion to String
System.out.println("\nres " + res.toString());
// conversion to MatrixValueI
MatrixValueI mat = res.toVecMat();
System.out.println("matrix " + mat.toString());
// conversion to array
if(res.getDims().is1D())
{
double vecArray[] = (double []) res.toArray();
System.out.print("[");
for(int i=0;i