HP41: accuracy of 13-digit routines
09-02-2015, 11:05 AM (This post was last modified: 09-02-2015 11:07 AM by Ángel Martin.)
Post: #5
 Ángel Martin Senior Member Posts: 1,443 Joined: Dec 2013
RE: HP41: accuracy of 13-digit routines
(09-02-2015 10:18 AM)Dieter Wrote:  Thank you very much. So the 13-digit routines truncate after 13 digits. I assume this also applies to the transcendental functions (log, exp, trig etc.). Now if I set a WP34s to RM 4 (truncate) and apply a RSD 13 to every result, this should yield the same result as the 41's 13-digit routines?

Typically that seems to be the case: the 13-digit result is held in the {A,B} registers, with the 13-digit mantissa in B<12:0> and the sign and exponent in A. Once the math routine is done it transfers the mantissa from B to the C register, most usually using the instruction C=B M - thus it is a 10-digit version made by direct truncation.

I however have done some rounding *prior* to this truncation in some of my own math functions - hard to remember which ones though...

Cheers,
ÁM

"To live or die by your own sword one must first learn to wield it aptly."
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 Messages In This Thread HP41: accuracy of 13-digit routines - Dieter - 09-01-2015, 09:23 PM RE: HP41: accuracy of 13-digit routines - Thomas Klemm - 09-02-2015, 04:45 AM RE: HP41: accuracy of 13-digit routines - Dieter - 09-25-2015, 10:46 PM RE: HP41: accuracy of 13-digit routines - Joe Horn - 09-02-2015, 06:11 AM RE: HP41: accuracy of 13-digit routines - Dieter - 09-02-2015, 10:18 AM RE: HP41: accuracy of 13-digit routines - Ángel Martin - 09-02-2015 11:05 AM RE: HP41: accuracy of 13-digit routines - Michael Fehlhammer - 09-02-2015, 11:19 AM RE: HP41: accuracy of 13-digit routines - Ángel Martin - 09-02-2015, 12:03 PM RE: HP41: accuracy of 13-digit routines - Dieter - 09-02-2015, 06:07 PM RE: HP41: accuracy of 13-digit routines - Ángel Martin - 09-03-2015, 06:22 AM RE: HP41: accuracy of 13-digit routines - Dieter - 09-03-2015, 12:36 PM RE: HP41: accuracy of 13-digit routines - Ángel Martin - 09-03-2015, 01:33 PM RE: HP41: accuracy of 13-digit routines - Dieter - 09-03-2015, 06:17 PM RE: HP41: accuracy of 13-digit routines - Ángel Martin - 09-04-2015, 12:07 PM RE: HP41: accuracy of 13-digit routines - Dieter - 09-04-2015, 07:36 PM RE: HP41: accuracy of 13-digit routines - Ángel Martin - 09-04-2015, 09:53 PM RE: HP41: accuracy of 13-digit routines - Dieter - 09-04-2015, 10:24 PM RE: HP41: accuracy of 13-digit routines - Dieter - 09-25-2015, 01:53 PM RE: HP41: accuracy of 13-digit routines - Thomas Klemm - 09-25-2015, 11:33 PM

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