org.lsmp.djepExamples.GroupConsole Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jep Show documentation
JEP is a Java library for parsing and evaluating mathematical expressions.
The newest version!
/* @author rich
 * Created on 21-Mar-2005
 *
 * See LICENSE.txt for license information.
 */
package org.lsmp.djepExamples;

import org.nfunk.jep.Node;
import org.nfunk.jep.ParseException;
import org.lsmp.djep.groupJep.*;
import org.lsmp.djep.groupJep.groups.*;
import org.lsmp.djep.groupJep.interfaces.*;
import org.lsmp.djep.groupJep.values.*;
import org.nfunk.jep.type.Complex;
import java.math.*;

/**
 * Console application with handling for abstract groups 
 * @author Rich Morris
 * Created on 21-Mar-2005
 */
public class GroupConsole extends Console
{
	private static final long serialVersionUID = -3097491397108691409L;

	public static void main(String args[]) {
		Console c = new GroupConsole();
		c.run(args);
	}

	public String getPrompt()
	{
		return "GroupJep > ";
	}

	public void initialise()
	{
		j = new GroupJep(new Rationals()); 
		j.setAllowAssignment(true);
		j.setAllowUndeclared(true);
		j.setImplicitMul(true);
		j.addStandardConstants();
		j.addStandardFunctions();
	}

	public void initialise(Group g)
	{
		j = new GroupJep(g); 
		j.setAllowAssignment(true);
		j.setAllowUndeclared(true);
		j.setImplicitMul(true);
		j.addStandardConstants();
		j.addStandardFunctions();
	}

	public void printIntroText()
	{
		println("GroupJep: evaluation over abstract groups");
		printGroup();
		super.printStdHelp();
	}

	public void printGroup()
	{
		println("Current Group: "+((GroupJep) j).getGroup().toString());
	}
	public void processEquation(Node node) throws ParseException
	{
		Object value = j.evaluate(node);
		if(value instanceof HasComplexValueI)
			println(value.toString()+"="
				+((HasComplexValueI) value).getComplexValue());
		else
			println(value);
	}

	public boolean testSpecialCommands(String command)
	{
		GroupJep gj = (GroupJep) j;
		if(!super.testSpecialCommands(command)) return false;
		String words[] = split(command);
		if(words.length==0) return true;
		if(words[0].equals("group"))
		{
			if(words.length == 1) {	}
			else if(words[1].equals("Z")) {
				initialise(new Integers());
			}
			else if(words[1].equals("Q"))
			{
				initialise(new Rationals());
			}
			else if(words[1].equals("R") && words.length == 3)
			{
				initialise(new BigReals(
							Integer.parseInt(words[2]),
							BigDecimal.ROUND_HALF_EVEN ));
			}
			else if(words[1].equals("R") && words.length == 2)
			{
				initialise(new Reals());
			}
			else if(words[1].equals("P") && words.length == 3)
			{
				initialise(new PermutationGroup(
							Integer.parseInt(words[2]))
							);
			}
			else if(words[1].equals("Zn") && words.length == 3)
			{
				initialise(new Zn(new BigInteger(words[2]))); 
			} 
			else if(words[1].equals("Qu"))
			{
				initialise(new Quaternions());
			}
			else
			{
				println("invalid group spec "+command);
				return false;
			}
			printGroup();
			return false;
		}



		if(words[0].equals("extend"))
		{
			RingI ring = (RingI) gj.getGroup();

			if(words.length < 2)
				println("extend must have at least one argument");
			else if(words.length == 2) /* Add a free variable */
			{
				initialise(new ExtendedFreeGroup(ring, words[1]));
			}
			else /* extend by an algebraic number */
			{
				int deg = words.length-3;
				Number coeffs[] = new Number[deg+1];
				for(int i=0;i<=deg;++i)
					coeffs[i] = ring.valueOf(words[words.length-i-1]);
				Polynomial p1 = new Polynomial(ring,words[1],coeffs);

				initialise(new AlgebraicExtension(ring, p1));
			}
			printGroup();
			return false;
		}
		
		if(words[0].equals("setRootVal"))
		{
			String symbol = words[1];
			Complex val = new Complex(Double.parseDouble(words[2]),Double.parseDouble(words[3]));
			GroupI g = gj.getGroup();
			if(g instanceof FreeGroup) {
				boolean flag = ((FreeGroup) g).setRootVal(symbol,val);
				if(!flag) println("Failed to set root value, could not find symbol");
			}
			return false;
		}
		return true;
	}

	public void printHelp()
	{
		super.printHelp();
		println("'group'\tprints the current group");
		println("'group G'\tchanges underlying group to G");
		println("'group Z'\tintegers (arbitrary precision)");
		println("'group Q'\trationals");
		println("'group R'\treals, represented as Doubles.");
		println("'group R 3'\treals represented as BigDecimals with 3 decimal places");
		println("'group P 3'\tpermutation group on three symbols");
		println("\t[1,3,2]+[3,2,1] -> (3,1,2)");
		println("'group Zn 5'\tintegers modulo 5");
		println("'group Qu'\tQuarternions");
		println("'extend x'\textends current group by adding symbol x, i.e. a free group");
		println("\tsuch a group can be considered as the ring of polynomials");
		println("\tsimplification happens automatically");
		println("'extend t a b c'\talgebraic extensions generated by t");
		println("\twhere t is a root of the polynomial a t^2 + b t +c=0");
		println("\te.g  group extend t 1 0 1 gives complex numbers, t^2+1=0.");
		println("\tfor these groups there is a natural mapping to complex numbers and complex result is also printed.");
		println("'setRootVal t re im'\tsets the value of free variable 't' in a free group to complex number re+i im");
	}

}