org.lsmp.djepExamples.MRpDiffExample Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jep Show documentation
Show all versions of jep Show documentation
JEP is a Java library for parsing and evaluating mathematical expressions.
/* @author rich
* Created on 01-Apr-2005
*
* See LICENSE.txt for license information.
*/
package org.lsmp.djepExamples;
import java.util.Enumeration;
import java.util.Vector;
import org.lsmp.djep.djep.DPrintVisitor;
import org.lsmp.djep.matrixJep.MatrixJep;
import org.lsmp.djep.matrixJep.MatrixVariableI;
import org.lsmp.djep.mrpe.MRpCommandList;
import org.lsmp.djep.mrpe.MRpEval;
import org.lsmp.djep.mrpe.MRpRes;
import org.nfunk.jep.Node;
import org.nfunk.jep.ParseException;
/**
* An example of using MRpEval with differentation.
*
* @author Rich Morris
* Created on 01-Apr-2005
*/
public class MRpDiffExample {
MatrixJep mj;
MRpEval mrpe=null;
MRpCommandList allCommands[];
int xref,yref;
double xmin = -1.0,xmax = 1.0,ymin=1.0,ymax=1.0;
int xsteps = 100,ysteps = 100;
public static void main(String args[]) {
timePrint("\tStart");
MRpDiffExample surf = new MRpDiffExample();
timePrint("\tDone init");
try {
surf.compile("th=pi*x;phi=pi*y;f=[cos(th) cos(phi),sin(th) cos(phi),sin(phi)];dx=diff(f,x);dy=diff(f,y);dx^dy;");
timePrint("\tDone parse");
surf.calcMRPE();
surf.mrpe.cleanUp();
timePrint("\tDone mrpe");
} catch(Exception e) { System.out.println(e.getClass().getName()+": "+e.getMessage()); }
}
static long oldTime = 0;
public static void timePrint(String msg) {
long time = System.currentTimeMillis();
long timediff = time-oldTime;
oldTime = time;
System.out.println(""+timediff+"\t"+msg);
}
public MRpDiffExample() {
mj = new MatrixJep();
mj.setAllowAssignment(true);
mj.setAllowUndeclared(true);
mj.setImplicitMul(true);
mj.addComplex();
mj.addStandardConstants();
mj.addStandardFunctions();
mj.addStandardDiffRules();
mrpe = new MRpEval(mj);
//mj.getPrintVisitor().setMode(PrintVisitor.FULL_BRACKET,true);
mj.getPrintVisitor().setMode(DPrintVisitor.PRINT_PARTIAL_EQNS,false);
}
/**
* Compile a sequence of equations.
*
* @param text
*/
public void compile(String text)
{
mj.restartParser(text);
try
{
Vector eqns = new Vector();
Node n;
while((n = mj.continueParsing())!=null) {
Node n2 = mj.preprocess(n);
Node n3 = mj.simplify(n2);
eqns.add(n3);
}
// gets the top equation
Node topEqn = (Node) eqns.get(eqns.size()-1);
// differentiate it
Node dx = mj.differentiate(topEqn,"x");
Node dy = mj.differentiate(topEqn,"y");
// create a list of all variables needed to
// successfully evaluate topEqn, dx, and dy
Vector deps = mj.recursiveGetVarsInEquation(topEqn,new Vector());
deps = mj.recursiveGetVarsInEquation(dx,deps);
deps = mj.recursiveGetVarsInEquation(dy,deps);
// Compile all equations needed for successful evaluation
// of top, dx, dy
Vector coms = new Vector();
for(Enumeration en=deps.elements();en.hasMoreElements();) {
MatrixVariableI var = (MatrixVariableI) en.nextElement();
if(var.hasEquation()) {
Node eqn = var.getEquation();
System.out.print("Compiling "+var.getName()+"=");
mj.println(eqn);
coms.add(mrpe.compile(var,eqn));
}
else {
// The variable has no equation
System.out.println("Ignoring "+var.getName());
}
}
// compile the top equation and derivatives
System.out.print("Compiling "); mj.println(topEqn);
coms.add(mrpe.compile(topEqn));
System.out.print("Compiling "); mj.println(dx);
coms.add(mrpe.compile(dx));
System.out.print("Compiling "); mj.println(dy);
coms.add(mrpe.compile(dy));
// put into any array
int i=0;
allCommands = new MRpCommandList[coms.size()];
for(Enumeration en=coms.elements();en.hasMoreElements();++i)
allCommands[i] = (MRpCommandList) en.nextElement();
// finds the references for two variables
xref = mrpe.getVarRef(mj.getVar("x"));
yref = mrpe.getVarRef(mj.getVar("y"));
}
catch(ParseException e) {e.getMessage();}
}
public void calcMRPE() {
double topRes[]=null,dxRes[]=null,dyRes[]=null;
for(int i=0;i<=xsteps;++i) {
double x = xmin + ((xmax - xmin)*i)/xsteps;
mrpe.setVarValue(xref,x);
for(int j=0;j<=ysteps;++j) {
double y = ymin + ((ymax - ymin)*j)/ysteps;
mrpe.setVarValue(yref,y);
MRpRes res=null;
for(int k=0;k