A close friend of the family called Ulam an "imposing presence."
"One felt the weight of his erudition," she said.
But despite his imposing appearance, he had a softer side--"he wept over the death of our dog," Burgwin Ulam said.
Ulam was also an avid sports fan--a tennis player and Red Sox devotee.
"He will be buried in the Harvard plot [in Mount Auburn cemetery] overlooking Harvard Stadium, which he would love," Burgwin Ulam said.
Ulam is survived by his ex-wife and his sons, Alexander and Joseph Ulam.
According to Burgwin Ulam, despite their divorce, a sense of "deep love" pervaded their family life. She said she and her ex-husband had planned to re-marry.
A memorial service for Ulam will be held today at noon at Mount Auburn Cemetery.