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JEP is a Java library for parsing and evaluating mathematical expressions. Use groupId org.fudaa to deploy it in maven central
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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.PostfixMathCommand;
/**
* Extracts diagonal from a square matrix.
* getDiag([[1,0,0],[0,2,0],[0,0,3]]) -> [1,2,3]
*
* @author Rich Morris
* Created on 13-Feb-2005
*/
public class GetDiagonal extends PostfixMathCommand implements UnaryOperatorI
{
public GetDiagonal()
{
super();
this.numberOfParameters = 1;
}
public Dimensions calcDim(Dimensions ldim)
{
return Dimensions.valueOf(ldim.getFirstDim());
}
public MatrixValueI calcValue(MatrixValueI res, MatrixValueI lhs)
throws ParseException
{
MVector vec = (MVector) res;
Matrix mat = (Matrix) lhs;
if( vec.getNumEles() != mat.getNumRows()
|| vec.getNumEles() != mat.getNumCols())
throw new ParseException("getDiag requires a square matrix");
for(int i=0;i