Difference between revisions of "The Algorithm"
From Geohashing
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'''This time, we ''did'' invent the algorithm!''' | '''This time, we ''did'' invent the algorithm!''' | ||
| − | + | * The current date (in yyyy-mm-dd format) and the daily opening price of the [[Dow Jones Industrial Average]] are concatenated with a hyphen and fed through the [[wikipedia:MD5|MD5]] cryptographic algorithm to generate as pseudo-random string of 32 hexadecimal digits. | |
| − | + | ** If there is no opening price for the Dow, the opening price from its previous day of active trading is used instead. | |
| − | + | * The resulting string is split into two halves of 16 hexadecimal digits. | |
| − | + | * Each half-string is prepended with a decimal point (so as to represent a hexadecimal fraction) and is converted to a base-10 fraction. | |
| − | + | * The resulting decimal fractions are appended to the integral (lat,lon) values of any given [[graticule]] to produce that graticule's geohash target. | |
== Fractional hexadecimal to decimal calculation == | == Fractional hexadecimal to decimal calculation == | ||
Many online hex-to-dec converters do not support hexadecimal fractions. Here is one that does: | Many online hex-to-dec converters do not support hexadecimal fractions. Here is one that does: | ||
* [http://www.easysurf.cc/cnver17.htm#bf16tobf10 EasySurf.cc] | * [http://www.easysurf.cc/cnver17.htm#bf16tobf10 EasySurf.cc] | ||
Revision as of 22:34, 23 May 2008
This time, we did invent the algorithm!
- The current date (in yyyy-mm-dd format) and the daily opening price of the Dow Jones Industrial Average are concatenated with a hyphen and fed through the MD5 cryptographic algorithm to generate as pseudo-random string of 32 hexadecimal digits.
- If there is no opening price for the Dow, the opening price from its previous day of active trading is used instead.
- The resulting string is split into two halves of 16 hexadecimal digits.
- Each half-string is prepended with a decimal point (so as to represent a hexadecimal fraction) and is converted to a base-10 fraction.
- The resulting decimal fractions are appended to the integral (lat,lon) values of any given graticule to produce that graticule's geohash target.
Fractional hexadecimal to decimal calculation
Many online hex-to-dec converters do not support hexadecimal fractions. Here is one that does:
