Talk:HP-42S

Precision
--79.151.242.162 (talk) 11:49, 9 August 2015 (UTC) "25 digits internally" is not documented anywhere. Actually the old versions of the page have 15, which is what most people believe it is, that is 3 guard digits. After analysis of some particular results and the source code of other Saturn calculator (hpmuseum forum threads), apparently it works to double precision just for the trigonometric functions, that's all. No register is stored to "25 digits" and no other operation is performed to "25 digits", it's a hidden trick to improve range reduction.