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35s Minor Complaint and Minor Correction - Printable Version

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35s Minor Complaint and Minor Correction - Trent Moseley - 07-28-2007

Minor beef: The RND (round) function does't work on a complex number as it does on the 42s; you get "INVALID DATA". The wrong shift key is indicated for the RND (round) function on page G-13 of the User's Guide.

tm


Re: 35s Minor Complaint (RND) and Minor Correction - Karl Schneider - 07-29-2007

Hi, Trent --

Quote:
Minor beef: The RND (round) function does't work on a complex number as it does on the 42s; you get "INVALID DATA". The wrong shift key is indicated for the RND (round) function on page G-13 of the User's Guide.

Yep, I'd say that's either a bug, or the functional specification was undefined, so RND fell by default to "invalid for complex arguments".

Hmm, I'd never thought about that one, so I had to try it out:

RND for a complex number on the HP-42S rounds both components. This makes sense for its paradigm; to round only one component, use the following:

COMPLEX   (RPL "C->R") 
(x<>y for real)
RND
(x<>y for real)
COMPLEX (RPL "R->C")

On the HP-15C, RND operates only on the real component. This is consistent with its documentation on p. 24 of the Owner's Handbook, in that "Number Alteration Functions" operate only on the number in the display. This also makes more sense for its paradigm; to RND both parts, the following sequence is easier:

RND
Re<->Im
RND
Re<->Im

than for the user to separate and reassemble the components if only one component is to be RND'ed.

Another example of good thinking by those "A-team" H-P calculator engineers in the 1980's...

-- KS

Edited: 29 July 2007, 1:11 a.m.