Editing Geographic coordinate conversion (section)

==Change of units and format==

Informally, specifying a geographic location usually means giving the location's [[latitude]] and [[longitude]]. The numerical values for latitude and longitude can occur in a number of different units or formats:<ref>{{cite web|title=Coordinate transformer|url=http://www.ordnancesurvey.co.uk/gps/transformation|publisher=Ordnance Survey Great Britain|access-date=4 March 2014|archive-date=12 August 2013|archive-url=https://web.archive.org/web/20130812112214/http://www.ordnancesurvey.co.uk/gps/transformation|url-status=live}}</ref>

* [[sexagesimal degree]]: [[degree (angle)|degrees]], [[Minute of arc|minutes]], and [[Arcsecond|seconds]] : 40° 26′ 46″ N 79° 58′ 56″ W
* degrees and decimal minutes: 40° 26.767′ N 79° 58.933′ W
* decimal degrees: +40.446 -79.982

There are 60 minutes in a degree and 60 seconds in a minute. Therefore, to convert from a degrees minutes seconds format to a decimal degrees format, one may use the formula

: <math>\rm{decimal\ degrees} = \rm{degrees} + \frac{\rm{minutes}}{60} + \frac{\rm{seconds}}{3600}</math>.

To convert back from decimal degree format to degrees minutes seconds format,

: <math> \begin{align}
  \rm{absDegrees} & = | \rm{decimal\  degrees} | \\
  \rm{floorAbsDegrees} & = \lfloor \rm{absDegrees} \rfloor \\
  \rm{degrees} & = \sgn ( \rm{decimal\  degrees} ) \times \rm{floorAbsDegrees} \\
  \rm{minutes} & = \lfloor 60 \times (\rm{absDegrees} - \rm{floorAbsDegrees})\rfloor  \\
  \rm{seconds} & = 3600 \times (\rm{absDegrees} - \rm{floorAbsDegrees}) - 60 \times \rm{minutes} \\
\end{align} </math>
where <math>\rm{absDegrees}</math> and <math>\rm{floorAbsDegrees}</math> are just temporary variables to handle both positive and negative values properly.