Complex Number Juxtapositions


You can STORE a complex number on the 35s, but you can't ROUND one. You can ROUND one on the 42s but you can't STORE it.

You put one fire out and another one pops up someplace else. I know it's just an annoyance but -

"So near yet so far..."



Hi, Trent --

Regarding operations with complex numbers on the HP-35s:

"So near yet so far..."

Formal response: "I concur with your sentiments."

Informal response: "Amen, brother!"

Perhaps more annoying is that SHOW also doesn't work on a complex number, and that there is no simple way to separate the components of a complex number. Thus, the RND limitation can't be circumvented by applying RND to each part separately, but even if RND did operate on a complex number, SHOW won't verify that it worked as intended...

You can ROUND one on the 42s but you can't STORE it.

The second part of that statement is incorrect. A complex number can always be stored to a named variable, or it can be stored to a numbered register if the matrix of storage registers ("REGS") is dimensioned as complex:


Indeed, RND is applied to both parts of a complex number (in rectangular or polar mode) on the HP-42S. If the user wants to round only one component, the number can first be separated into two reals using COMPLEX.

Try this on an HP-42S: Enter a complex number with 12-digit mantissas for both components (say, pi and e^1), and assemble the number in POLAR mode using COMPLEX. SHOW will then display both components with their 12-digit mantissas. Then, do FIX 03, RND, and SHOW. You'll see 3.142 at angle 2.718 before and after SHOW. Change to RECT mode, and SHOW again. You'll see 12-digit rectangular-coordinate values for both components, indicating that RND was properly applied to the displayed value, even though the number may have been internally represented in rectangular form all along.

-- KS

Edited: 18 Oct 2007, 12:26 a.m.


Thank you Karl.


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