Changing Of The Guard

[Joe Horn]

(04-22-2014 05:28 AM)Matt Agajanian Wrote:  Although, as I regard HP in high technological respect, their usage of guard digits in their calcs is quite obscure and I do not recall in any manuals that calculations are carried past 10 digits of accuracy (unless it's explicitely stated in some of their manuals and I must've missed the fine print somwhere).

It's explained in at least some HP manuals. For example, the 32SII says on page 1-16, "All numbers are stored with 12-digit precision.... During some complicated internal calculations, the calculator uses 15-digit precision for intermediate results."

Ever since Dennis Harm's famous "The New Accuracy: Making 2^3=8" article was written (HP Journal, October 1976, pages 16-17), every HP BCD calculator has used 3 extra digits during internal calculations, and at least some of their manuals have in fact explained this.