org.lsmp.djep.vectorJep.function.Trace Maven / Gradle / Ivy
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JEP is a Java library for parsing and evaluating mathematical expressions.
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/* @author rich
* Created on 13-Feb-2005
*
* See LICENSE.txt for license information.
*/
package org.lsmp.djep.vectorJep.function;
import java.util.Stack;
import org.lsmp.djep.vectorJep.Dimensions;
import org.lsmp.djep.vectorJep.values.*;
import org.nfunk.jep.ParseException;
import org.nfunk.jep.function.*;
/**
* Calculate the trace of a matrix
* trace([[1,2],[3,4]]) -> 1+4 = 5
*
* @author Rich Morris
* Created on 13-Feb-2005
*/
public class Trace extends PostfixMathCommand implements UnaryOperatorI
{
Add add = new Add();
Multiply mul = new Multiply();
public Trace()
{
super();
this.numberOfParameters = 1;
}
public Dimensions calcDim(Dimensions ldim)
{
return Dimensions.ONE;
}
public MatrixValueI calcValue(MatrixValueI res, MatrixValueI lhs)
throws ParseException
{
if(!(res instanceof Scaler))
throw new ParseException("trace: result must be a scaler");
if(!(lhs instanceof Matrix))
throw new ParseException("trace: argument must be a matrix");
Matrix mat = (Matrix) lhs;
if( mat.getNumRows()!= mat.getNumCols())
throw new ParseException("trace: argument must be a square matrix "+mat);
if(mat.getNumRows() == 2)
{
res.setEle(0,add.add(mat.getEle(0,0),mat.getEle(1,1)));
}
else if(mat.getNumRows() == 3)
{
res.setEle(0,add.add(mat.getEle(0,0),add.add(mat.getEle(1,1),mat.getEle(2,2))));
}
else
{
Object val = mat.getEle(0,0);
for(int i=1;i