Re: Periods After Whole Numbers

Subject: Re: Periods After Whole Numbers
From: "Huber, Mike" <Mike -dot- Huber -at- SOFTWARE -dot- ROCKWELL -dot- COM>
Date: Mon, 16 Sep 1996 10:25:52 -0400

A very good point!
I had a situation a while back in which an editor changed
580K
to
593920 bytes

It calculates out, but it implies much more precision. 580K means
somewhere above 575K but below 585K (a range of 10K),
while 593920 bytes means somewhere between 593915 and 593925 (a range of
10 bytes).

The 580K number was not exact, it was a guideline for how much memory a
program needed to run reasonably well. The program used dynamic memory
allocation, and the concept of "reasonably well" wasn't tightly defined.
We had tested the software to run in 580K, but I felt the 593920 number
implied that it was a magic number - 593920 bytes and everything's cool,
593919 and you are out of luck, 593921 and you are wasting RAM.

The rule (as I recall from engineering classes a long time ago) is that,
when you multiply, the number of significant digits in the result is the
same as the number of significant digits in the least precise number. In
the example above, that works out as

580 * 1024 = 590000

because the 580K only has two significant digits. 580.K has three, so the
answer would be 594000 bytes.

----------
From: KNOXML1[SMTP:KnoxML1 -at- TEOMAIL -dot- JHUAPL -dot- EDU]
Sent: Monday, September 16, 1996 8:55 AM
To: Multiple recipients of list TEC
Subject: Re: Periods After Whole Numbers

Someone (I forget who--sorry) wrote:
>>My supervisor insists on putting periods after whole numbers. For
>>example, he writes "200. kg" rather than just "200 kg".

And Kris Olberg replied:

>I can't think of any GOOD reason to use it. Reduce ambiguity? No.
>Significant digits? No. (In the example, if there was only one
significant
>digit, would you write that as 2.00 kg?) Because it's dictated by
folklore?
>Emphatically no.

>I can think of GOOD reasons to not use it. 1) It takes up one extra byte
of
>storage space every time it's used, 2) it's extra information the read
must
>process for no good reason, and 3) you're probably one of only a handful
of
>writers in the world that does it.

Kris is right, but there's another very good reason to avoid the decimal
point:
It implies that the zeros in 200 kg are mathematically siginificant.
(That is
the point of its use in accounting. It says that the $200 is no more
that
$200.49 and no less than $199.50; it was not rounded from $203 or $195).
Your
supervisor is not reducing ambiguity, he is asking you to change the
meaning
and
mislead the reader about the precision of the number.

Yes, lose the period!

Margaret Knox Morris
Techincal writer/editor
Margaret -dot- Morris -at- jhualp -dot- edu

Searchable archives located at http://www.documentation.com/
ALL questions or problems concerning the list
should go to the listowner, Eric Ray at ejray -at- ionet -dot- net -dot-

Searchable archives located at http://www.documentation.com/
ALL questions or problems concerning the list
should go to the listowner, Eric Ray at ejray -at- ionet -dot- net -dot-


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