This is sad news indeed. A couple of things about Roger:<p>The less important one: his Erdős number is 2, thanks to his coauthoring "A generalization of the fast LUP matrix decomposition algorithm and applications" with Shlomo Moran whose Erdős number is 1. (It's not shown on his Wikipedia page, but he's listed at <a href="https://en.wikipedia.org/wiki/List_of_people_by_Erd%C5%91s_number#H_2" rel="nofollow">https://en.wikipedia.org/wiki/List_of_people_by_Erd%C5%91s_n...</a> .)<p>Roger was a great example of "precision with humanity", like Ken Iverson. This was obvious in many ways, and here's an unusual one: I've managed various technical groups over the decades, and Roger was the only person who, when he said he'd have something done by a particular date, was finished by that date, every single time. When he ran into a snag I would sometimes tell him that it would be okay if it took longer, but no, as far as he was concerned he'd made a commitment and was going to meet it, even if that meant working a lot of extra hours.<p>Rohan Jayasekera