William Kahan

William Kahan (b. 1933) is a Canadian-American mathematician and computer scientist who, as a paid consultant to Intel in the late 1970s, designed the arithmetic for the 8087 floating-point coprocessor and then carried that design into the IEEE p754 standards committee, where his draft ("K-C-S," co-written with Jerome Coonen and Harold Stone) became the basis of the IEEE 754 floating-point standard ratified in 1985. He received the 1989 ACM Turing Award largely for this work.

In this vault Kahan is the connective figure beneath the numerical-analysis lineage: the standard his committee produced is the ground both the Patriot missile's timekeeping and the Pentium FDIV bug stand on — one working around its rules, one failing to implement them correctly in silicon.

References

• claim-kahan-8087-spec-became-ieee-754 — his engagement by Intel and the K-C-S draft's adoption as IEEE 754's basis.
• claim-palmer-recruited-kahan-as-consultant-for-i8087-arithmetic — how and why Intel recruited him.
• claim-kahan-declined-to-bill-intel-for-8087-work-transferred-to-ieee-754 — the ethical line he drew around the transfer.
• claim-ieee-754-extended-precision-explicit-bit-inherited-from-intel-8087 — the one respect in which the 8087-to-754 lineage was selective, not total.