Bruce Reznick
IIn the Fall of 1970, in my second year at Caltech, I was a homework grader for a section of calculus. Darrell was so happy that he was able to solve a particularly difficult problem, that he wrote on his paper: MATH IS GROOVY.
I picked this up this phrase as my personal motto, had it on my door for many years, first as a student, and then as a math professor at various schools. Darrell and I had a very nice email conversation in 2009 where we confirmed our memories of the origins of MATH IS GROOVY.
I offer my deepest condolences to the friends and family of Darrell Peterson.

