Nice post, as always, Rick.

While you did not emphasize this point in this post, you illustrate the important point that many times in IML you can use functions, in this case ALL, to avoid writing loops that address individual matrix elements.

When I was a SAS/STAT developer, I frequently found myself faced with the question "Are these two values equal?" with the special case "Is this value equal to 0?" being the most common. I did not always choose the same method (not that I am advocating anything different in your case). I just wanted to point out that this particular section of the PROC COMPARE documentation often proved to be helpful. https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.5/proc/p0bbu58eqgufwzn16zafm1hvzfw2.htm