Research series

The Last Bit

How we worked out what Excel computes, down to the last bit, in reading order. Articles are written to be read. Working notes were kept during the work and are marked as such; later notes correct earlier ones.

Measurement is one part of this project's method. The work also uses published algorithms, instruction manuals and licensed translations. Every figure applies to its recorded inputs, Excel builds and platforms.

  1. The Last BitArticle · July 2026How machines compute exp and sin, and what two disagreeing Excels showed. PDF
  2. The primitive campaignWorking notes · July 2026Twenty-seven stories from identifying exp, expm1, GAMMALN and the payment functions, sections 1 to 28.
  3. The error-function swarmWorking notes · 21 August 2026Rival theories of ERF, GAUSS and NORMSDIST, tested against each other.
  4. The first honest lookWorking notes · 24 September 2026What the first strict count of matching functions showed.
  5. The shape of the codeDraft article · 4 November 2026Searching for the short programs that explain Excel's rounding.

Research log

The rounds after these notes are kept as a terse working log in the public repository DnaCalc/DnaCalc-Research, with their evidence.