}
// solve for Rx = b using the standard upper triangular solver
solveU(R.asDoubleArray(),a.asDoubleArray(),numCols);
// save the results
double[]data = X.asDoubleArray();
for( int i = 0; i < numCols; i++ ) {
// X.data[i*X.columnCount()+colB] = a.data[i];
data[i*X.columnCount()+colB] = a.data[i];
}
}