for( int i = 0; i < N; i++ ) {
// reshape temporary variables
A_small.reshape(QR.numRows-i,QR.numCols-i,false);
A_mod.reshape(A_small.numRows,A_small.numCols,false);
v.reshape(A_small.numRows,1,false);
Q_k.reshape(v.getNumElements(),v.getNumElements(),false);
// use extract matrix to get the column that is to be zeroed
CommonOps.extract(QR,i,QR.numRows,i,i+1,v,0,0);
double max = CommonOps.elementMaxAbs(v);