final int upRowOffset = j*innerSize; // Offset of a row before (locate upper) the current row.
acc.setFrom(LU, j*size + k, errorLU); // Same column than the diagonal element, but in the upper row.
for (int i=0; i<innerSize; i++) { // Apply to all columns in the upper row.
rat.setFrom(elements, rowOffset + i, errorOffset);
rat.multiply(acc);
rat.subtract(elements, upRowOffset + i, errorOffset);
rat.negate();
rat.storeTo(elements, upRowOffset + i, errorOffset);
}
}
}