Author: Greg_L_at_Wikipedia

Description:
This is a continuation of Bugzilla 13025 and should be considered its replacement.

A template [[Template:Val]] has to use math-based methods to parse the string in order to count digits and place gaps between the digits. This technique is prone to rounding errors. Even though the template has an error-checking ability, it still generates improper strings. For instance, {{val|6.02214184||e=23}} will generate 6.022 141 839 × 10^23 (note the “39” instead of the “4”).

Note how this tool is used (with work-arounds) here on [[Kilogram]]

http://en.wikipedia.org/wiki/Kilogram#Proposed_future_definitions

What is desperately needed are new parser functions that will permit the simple counting of characters to delimit numeric strings rather than math-based parser functions. This will allow the creation of a new magic word by the name of {{delimitnum}}. Note that there is already a template by the same “delimitnum” name. However, it is even more prone to rounding errors that {{val}} because it has no error checking. {{Delimitnum}} should be replaced by a parse function as proposed herein.

Delimitnum’s functionality is largely described here:

http://en.wikipedia.org/wiki/Wikipedia_talk:Manual_of_Style_(dates_and_numbers)/Archive_94#Grouping_of_digits_after_the_decimal_point_.28next_attempt.29

It was extensively discussed and voted upon here…

http://en.wikipedia.org/wiki/Wikipedia_talk:Manual_of_Style_(dates_and_numbers)/Archive_94#Continuing_Discussion.2C_specifically_regarding_latest_nutshell_proposal

on WT:MOSNUM and was well received here on WT:MOS:

http://en.wikipedia.org/wiki/Wikipedia_talk:Manual_of_Style/Archive_97#Exponential_notation

…where its functionality tweaked.

Here is a nutshell of how the new, replacement delimitnum magic word should work:

The magic word would parse as follows:

{{delimitnum: (value) | (uncertainty) | (base–ten exponent) | (unit symbol) }}

It would use span-based tags (e.g. <span style="margin-left:0.25em">) to space out characters without actually generating a separate character (so values copied and pasted into programs like Excel, where they would be treated as true numbers). The template would replace hand-coded strings such as this:

6.022<span style="margin-left:0.25em">461<span style="margin-left:0.2em">79</span></span>(30)&thinsp;×&thinsp;10²³&nbsp;kg

The parsing and spacing logic would be as follows:

Q1: Are there five or more undelimited digits remaining after the decimal marker? No=Stop / Yes=Advance three digits and prepare to add span gap. Goto Q2.
Q2: Is the span gap to be added following the digit “1”? No=Add a span gap of 0.25 em and then goto Q1 / Yes=Add a span gap of 0.2 em and then goto Q1.

The exact em widths chosen above produce the best looking results on the widest range of computing platforms. Some browsers resolve to 0.05 em. Others don’t and round up whereas others don’t round up. These characteristics are exploited to our advantage. Note also that a span gap following the digit 1 is different (0.2 em) v.s. that used for the others.

As mentioned above, details can be found here:

http://en.wikipedia.org/wiki/Wikipedia_talk:Manual_of_Style_(dates_and_numbers)/Archive_94#Grouping_of_digits_after_the_decimal_point_.28next_attempt.29

Note however, that since the above thread was archived, the spaces on each side of the “x” (multiply) sign have changed to thinspaces (&thinsp;) per the above cited discussions on WT:MOS

Version: unspecified
Severity: enhancement