The Museum of HP Calculators

HP Forum Archive 18

 HP41 Mcode Entrypoint for 'high precision numbers'Message #1 Posted by PeterP on 29 July 2008, 12:53 p.m. Hi, In PPCJ-V10-N7 Charles Bouldin talks about the normal arithmetic entrypoints ADD2_10 etc. In his first paragraph he also says "... additional entry points for high precision numbers which occupy a pair of addresses exist but will not be discussed here". Does anyone else know about this entry-points and how to use them? Thanks! Cheers Peter

 Re: HP41 Mcode Entrypoint for 'high precision numbers'Message #2 Posted by Eric Smith on 29 July 2008, 5:28 p.m.,in response to message #1 by PeterP Addresses (hexadecimal): ```ad2-10 1807 ad1-10 1809 ad2-13 180c mp2-10 184d mp1-10 184f mp2-13 1852 dv2-10 1898 dv1-10 189a dv2-13 189d ``` Comments from the source code: ```****************************************************** * common math entries *** * if number is 2-10, *** * then form is: *** * A has 10 digit form *** * C has 10 digit form *** * if number is 1-10, *** * then form is: *** * A has sign and exp *** * B has 13 digit mantissa *** * C has 10 digit form *** * if number is 2-13, *** * then form is: *** * A and B as in 1-10 *** * M has sign and exp *** * C has 13 digit mantissa *** * *** * on exit, C has 10 digit form *** * A and B have 13 digit form *** * *** ****************************************************** ```

 Re: HP41 Mcode Entrypoint for 'high precision numbers'Message #3 Posted by PeterP on 30 July 2008, 1:37 p.m.,in response to message #2 by Eric Smith Thanks Eric! Now I just have to figure out how to use them :-) Cheers Peter PS: it would appear that they are not double precision but just 13 digits instead of 10, correct?

 Re: HP41 Mcode Entrypoint for 'high precision numbers'Message #4 Posted by Eric Smith on 30 July 2008, 2:37 p.m.,in response to message #3 by PeterP Yes, 13-digit mantissa. The intent was that they provide more precision for intermediate results in calculations of the elementary functions (trig, logs, exponentials, etc). The extra 3 digits makes a big difference, though it isn't sufficient to guarantee correct rounding for all cases.

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