Template:Ahn convert

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Purpose: Given a article name and an ahnentafel number in parens, this stores the pair converted for the generation immediately following.

Parameters:

• 1 = an article with ahnentafel as extracted from the ahnentafel property eg: Gerrit Jan te Kolstee (1758-1797) (4)
• motherside = 1 if the tree is from the mother's side of the family. Default is zero (father's side).

How this black box works on the inside

For folks into math: we use a log function to derive the generation corresponding to the power of 2 base of the ahnentafel number. Upshifting or down shifting a generation is then a trivial operation.

For non math folks: Here is an illustration of how the number conversion works. First, examine the patterns of progression in ahnentafel numbers:

• Gen0 Adam 1
• Gen1 Adam 2; Eve 3; child's ancestors: = 2^1 (+1)
• Gen2 Adam 4; Eve 5; Fred 6; Ethyl 7; Darren 2; Samantha 3 ancestors: take Gen1, father side and add 2, mother side add 4.
• Gen3 Adam 8; eve 9 Fred 10; Ethyl 11; Derwood 4; Samantha 5
• Gen3 (adam on mother's side:) Adam 12 Eve 13 Fred 14 Ethyl 15....

• Generalization of pattern:
  • If ahn <4 add 2^1 if male, +2^2 if female
  • If ahn <8 add 2^2 if male, +2^3 if female
  • If ahn <2^4 add 2^3 if male, +2^4 if female
  • Refined: note the centrality of the generation#. The general rule is you always add 2^generation number if the tree is from the father, and add 2^(generation number+1) if from the mother. So how do we derive it. Ok finding the exponent of 2 is a log base 2 transform. #expr has logN (ln), so we can do this. To get log2 from ln, multiply 1/ln(2) times the ln of the ahn# and you have the log base 2. ln(2) is about 1.44 so we just multiply with that and round down to the nearest integer. That's your generation number (exp2base)
    • Formulas: exp2base= floor( ln(AHN)*1.44 ) btw- floor means round down to the greatest integer less than x
      • ahn=1734, generation = 10
        • adding 1734 from a father's tree becomes 2758
        • adding 1734 from a mother's tree becomes 3782
          • calculation: {{#expr:1734 + 2^(floor( ln(1734)*1.44 )+1)}}
    • this power of 2 "exp2base" number is just another word for Generation #.