public Vector columnSums() throws MatricksException {
Vector sums = new DenseDoubleVector(numCols());
MatrixCursor cursor = cursor();
while (cursor.next()) {
sums.set(cursor.col(), cursor.val() + sums.get(cursor.col()));
}
return sums;
}
public Vector rowSums() throws MatricksException {
// TODO: can change this to a lower level interface,
// taking in an array of doubles and not allocating ... ?
Vector sums = new DenseDoubleVector(numRows());
// TODO: optimize out row() with local var? microopt, measure speed
MatrixCursor cursor = cursor();
while (cursor.next()) {
sums.set(cursor.row(), cursor.val() + sums.get(cursor.row()));
}
return sums;
}
/*
* A = A ./ (x*x')
*/
public void dotDivOuterProd(Vector x) {
MatrixCursor mCursor = cursor();
while (mCursor.next()) {
mCursor.set(mCursor.val() / (x.get(mCursor.row()) * x.get(mCursor.col())));
}
}