Re: Mike Sebastian's Calculator Forensics Message #13 Posted by Gerson W. Barbosa on 9 Mar 2011, 8:21 a.m., in response to message #10 by Paul Dale
Paul,
The WP34s displays 9.00000000003, that is, the internal result is rounded to the number of digits of the display. HP used to round the result and truncate it to the number of digits in the display at the end of each operation. Thus, the HP42S displays 8.99999864267. HP's method makes sense because the results of the operations are coherent to the actual figures of the operands the user has access to (by examining their mantissas, for instance).
I assume the 34s is a 16digit device, but the calculations are carried out with extra guard digits, otherwise it wouldn't achieve the correct rounded 16digit result we see. Another reason to get the WP34s as soon it's available :)
Correct result for various numbers of digits in this old thread.
Regards,
Gerson.
