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The following documentation is transcluded from Template:Precision/doc.

The Template:Precision determines the precision (as a count of decimal digits) for any amount, large or negative, using a fast algorithm. It can also handle a trailing decimal point (such as "15." or "-41.") or trailing zeroes (such as "15.34000" having precision as 5 decimal digits). For fractional input it returns the base ten logarithm of the numerator.

Examples

{{Precision|1111.123456789}} 9
{{Precision|1111.12345678}} 8
{{Precision|1111.1234567}} 7
{{Precision|1111.123456}} 6
{{Precision|1111.12345}} 5
{{Precision|1111111111.12345678}} 5
{{Precision|1111111111.1234567}} 5
{{Precision|1111111111.123456}} 5
{{Precision|1111111111.12345}} 5
{{Precision|1111111111.1234}} 4
{{Precision|1111111111.123}} 3
{{Precision|1111111111.12}} 2
{{Precision|1111111111.1}} 1
{{Precision|1111111111.10}} 2
{{Precision|1111111111.100}} 3
{{Precision|1111111111.1000}} 4
{{Precision|1111111111.10000}} 5
{{Precision|1111111111}} 0
{{Precision|1111111110}} -1
{{Precision|1111111100}} -2
{{Precision|1111111000}} -3
{{Precision|1111110000}} -4
{{Precision|1111100000}} -5
{{Precision|1111000000}} -6
{{Precision|1110000000}} -7
{{Precision|1100000000}} -8
{{Precision|0}} -6
{{Precision|1}} 0
{{Precision|22.45}} 2
{{Precision|22.12345}} 5
{{Precision|22}} 0
{{Precision|22000}} -3
{{Precision|-15.275}} 0
{{Precision|-15.2500}} 0
{{Precision|23000222000111.432}} 1
{{Precision|-15.123}} 0
{{Precision|0.09}} 2
{{Precision|0.88}} 2
{{Precision|880000}} -4
{{Precision|90000000}} -7

Known bugs

  • For numbers in scientific notation, the precision is typically returned as too low by 1 decimal place. Example: {{precision |7.1234E+06}} → -2 (should be precision as 4 decimal digits, not 3).
  • Large numbers are limited to 11 trailing zeroes, so even larger numbers still report precision as being -11, such as 9 trillion: {{precision|9000000000000}} → -12 (should be: -12).

Technical notes

  • NOTE A1: This template determines the precision of decimals by counting the length of the numeric string (in a #switch comparing lengths of padded strings), then subtracting integer length, minus the decimal point, and minus 1 if negative. For integers, 1 place is subtracted for each trailing 0 on the integer. For fractions, any prior count is cleared x 0, then returns the base ten logarithm of denominator: (..prior...)*0 + (ln denom / ln 10).
  • NOTE D2: The check, for whole integers, compares the amount versus appending "0" at the end: when the amount is a decimal, then the value is unchanged by appending 0 at the end: so 5.23 = 5.230 is true, whereas for whole integers, it would be: 5 = 50 as false, due to values becoming n*10 for integer n. So, for integer n, the check rejects: n = n0 as false; hence n is integer.
  • NOTE M3: The magnitude of the integer portion is calculated by logarithm of the floor of absolute value (divided by natural logarithm of 10 to adjust for e=2.71828*), as: ln (floor( abs(-0.050067) )+0.99 )/ln10 Function floor(x) trims the decimal part, to leave the whole count: 0-9 yield 0, 10-19 as 1, 1000-1999 as 3. The abs(x) avoids floor of negatives, floor(-0.1)= -1, hence using abs(x) ensures -0.1 floors to 0 not -1. Near zero, the +0.99 avoids invalid log of 0, but does not round-up any decimals, already floored as nnn.00. Complexity is 6 operations: floor of abs( {1} ) +0.99 then log10x (lnx ÷ ln10), then floor that logarithm ratio. Decimals -1 < x < 1 yield -1, avoiding log 0.001 = -3.
  • NOTE N4: Nesting of if-else and nested templates is kept to a minimum, due to the MediaWiki 1.6 limit of 40 levels of if-logic for all nested templates used together. Template {ordomag} was omitted to avoid 2 more levels of nested templates. Template {Precision} had 8 levels, and this template was trimmed to only 5 levels.
  • NOTE S5: The #switch is run with "x" prepended in front of the amount, otherwise a #switch will compare as numeric where "2" would match "2.0" even though "2" is length 1 so "x2" no longer matches with "x2.0" as non-numeric. The #switch will exit on the first match, so smaller lengths are compared first, to avoid extra comparisons for more rare, longer numeric strings up to 41 long.
  • NOTE W6: The check for integers with whole end-zeroes uses typical n=n/10*10, for each power of 10, where whole millions match: {{#ifexpr: {1}=floor( {1}/1E6 )*1E6| }} Previously, {Precision} had tried to use "round" to detect end-zeroes but "round" loses precision at -5, so, n00000 round -5 differs from n00000 slightly, and comparisons to exact rounded amounts failed to match some numbers when 6 or more zeroes "n000000".
  • NOTE Z7: The check on zero for any .00000 compares adding 1 to the amount, versus appending "1" at the end: if the amount is a decimal, then adding 1 will be larger than appending 1 at the end: 0.00 + 1 > 0.001, whereas for whole zero, it would be: 0+1 > 01 as false, due to the value being the same. So, for integer 0, the check rejects: 0+1 > 01 as false; hence whole 0 is integer.

See also

This page uses content from the English language Wikipedia. The original content was at Template:Precision/doc. The list of authors can be seen in the page history. As with this Familypedia wiki, the content of Wikipedia is available under the Creative Commons License.
This page uses content from the English language Wikipedia. The original content was at Template:Precision. The list of authors can be seen in the page history. As with this Familypedia wiki, the content of Wikipedia is available under the Creative Commons License.
Community content is available under CC-BY-SA unless otherwise noted.