On 13/01/16 18:33, Rick C. Hodgin wrote:
On Wed, Jan 13, 2016 at 1:24 PM, Wols Lists <antlists@youngman.org.uk
<mailto:antlists@youngman.org.uk>> wrote:
On 13/01/16 17:37, Rick C. Hodgin wrote:
> Wol, I don't understand your objection. You have seen the
spreadsheet I
> created which demonstrates the various behaviors. Which one of
them is
> incorrect?
Sorry, I haven't seen the spreadsheet ...
>
> The whole purpose of the Metric add-on is to auto-range by
default, but
> to allow a user to explicitly set a range. I know in
semiconductors,
> for example, that I'll be working in nanoseconds or picoseconds.
As
> such, I want all of my cells to be in those ranges, so I will set
that
> option. I want to see things from that base, while maintaining
the real
> number in memory.
>
> This is what Metric would do. It would maintain the real value in
> memory, and then display it adjusted for the appropriate metric
base.
>
> You'll have to give me an example of what you're talking about
because
> right now I don't understand. Remember also that every cell can
have
> its own settings, so it would be inappropriate to not have
auto-ranging
> values when surrounding values nearby might be in completely
different
> bases. It is more appropriate to have auto-ranging values by
default,
> and then to have an explicitly-set range when required (such as
always
> displaying nanoseconds, or picoseconds, so that everything is then
in
> the common form for easy comparison).
Okay, copying your example that I've just found ...
> The important part of the Metric feature is that it always wraps
the
value to the
> nearest power of 3, and shows values in those powers. 0.1234
would be
shown
> as 123.4 milliunits, or 1,234 microunits,
Correction: should be 123,400 microunits.
If the user does NOT EXPLICITLY choose units, milli-units, or
micro-units then BOTH of the first two examples are CORRECT and the
last
one is wrong.
It's relative to the actual value, Wol. A value of 1 is one unit. A
value of .1 is 100 milliunits.
No no no - I get that.
To address your need, however, it could be an add-in for a bias,
indicating that the value specified is already in nanounts, and
therefore it adjusts accordingly.
That is, if the user has not told you, how do you choose between
0.1234
units, or 123.4 milli-units. The correct answer is you cannot. At
school, I would have been expected to use 123.4 milli-units. Other
people would have said "hey, it's 0.1234 units".
But if the user hasn't said anything, then 123,400 micro-units is
wrong
by all standards :-)
No. If the value is .1234 then it is 123,400 micro-units because you
assume that 1.0 is in units. But, as you indicate, it could be altered
so that there could be a bias to indicate the 1.0 value begins at some
point.
If the the value is .1234 then yes it is 123,400 micro-units. But to
DISPLAY it as 123,400 micro-units (unless the user has explicitly asked
for it) is wrong. THAT is what I'm getting at.
Basically, what I am saying is that if the user does not explicitly
specify what units they are asking for, then the following equation
MUST
be true ...
( TRUNCATE( MANTISSA) == 0 ) IS CONSTANT
I don't understand what you mean here. I understand what a mantissa is,
but to truncate the mantissa means you are using the implicit-1 value,
which makes the binary fraction 1.000..., resulting in a value of 1.0 in
base-10. This results in a single unit-value, which is what the current
Metric definition and example states, and would provide for.
(Whether the constant is TRUE or FALSE is a matter of convention.
This
should presumably be a spreadsheet-wide setting.)
Put otherwise, if I present you with three numbers, 123, 12.3 and
1.23
you can either leave them ALL alone, or convert them ALL to 0.123e3,
0.0123e3 and 0.00123e3. What you mustn't do is convert some of them.
I agree. In the case of Metric, none of them would be converted except
for display. It would indicate 123 units, 12.3 units, 1.23 units. They
would remain unaltered internally.
Sorry, that formula applies to the DISPLAY format. So if my convention
is FALSE, I can NOT display 0.1234 as "0.1234 units" because the
DISPLAYED truncated mantissa is 0. I have to coerce the DISPLAY to 123.4
milli-units, because the truncated mantissa is now 123 and that's okay.
Likewise, if you're given 12.3, 1.23, and 0.123 you then MUST convert
SOME of them, to 12.3, 1.23, and 123e-3, OR to 0.0123e3, 0.00123e3,
and
0.123.
In this case, it would be 12.3 units, 1.23 units, 123 milliunits. The
purpose of Metric, by default, is to auto-range the values so you are
not looking at lengthy decimals with leading 0s, or lengthy values with
trailing 0s before the decimal point. You get it into the appropriate
metric range, and view it there. However, should you want to look at
everything in terms of millivolts, for example, then you can set that,
and then the values shown will all be relative to 0.001 being 1
millivolt. And, based on what you've said above, a bias could be added
so that the base units is given already in milli-units, so that 1.0
would actually be 1 millivolt, but that would be additional information
beyond my original proposal, but still acceptable.
I have one other suggestion I'd like to add after this one, and it is to
include commas in the decimal component, so that a large value with a
large value would result in: 1,234,567,890.098,754,432,1
That's good. But bear in mind national conventions. We're using a dot to
indicate a decimal point, and we use either commas or spaces to indicate
thousand separators. Bear in mind, however, that some cultures (many
European) use the dot as a thousand separator and a comma as the decimal
point. So that needs to be configurable too.
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