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Standard deviation for geographic points


[latdev,londev] = stdm(lat,lon)
[latdev,londev] = stdm(lat,lon,ellipsoid)
[latdev,londev] = stdm(lat,lon,units)


[latdev,londev] = stdm(lat,lon) returns row vectors of the latitude and longitude geographic standard deviations for the data points specified by the columns of lat and lon.

[latdev,londev] = stdm(lat,lon,ellipsoid) specifies the shape of the Earth to be used by the ellipsoid, which can be a referenceSphere, referenceEllipsoid, or oblateSpheroid object, or a vector of the form [semimajor_axis eccentricity]. The default ellipsoid is a unit sphere. Output measurements are in terms of the distance units of the ellipsoid vector.

[latdev,londev] = stdm(lat,lon,units) indicates the angular units of the data. When you omit units, 'degrees' is assumed. Output measurements are in terms of these units (as arc length distance).

If a single output argument is used, then geodevs = [latdev longdev]. This is particularly useful if the original lat and lon inputs are column vectors.


Determining the deviations of geographic data in latitude and longitude is more complicated than simple sum-of-squares deviations from the data averages. For latitude deviation, a straightforward angular standard deviation calculation is performed from the geographic mean as calculated by meanm. For longitudes, a similar calculation is performed based on data departure rather than on angular deviation. See Geographic Statistics for Point Locations on a Sphere in the Mapping Toolbox™ User's Guide.


Create latitude and longitude lists using the worldcities data set and obtain standard distance deviation for group (compare with the example for stdist):

cities = shaperead('worldcities.shp', 'UseGeoCoords', true);
Paris = strcmp('Paris',{cities(:).Name});
London = strcmp('London',{cities(:).Name});
Rome = strcmp('Rome',{cities(:).Name});
Madrid = strcmp('Madrid',{cities(:).Name});
Berlin = strcmp('Berlin',{cities(:).Name});
Athens = strcmp('Athens',{cities(:).Name});
lat = [cities(Paris).Lat cities(London).Lat...
       cities(Rome).Lat cities(Madrid).Lat...
       cities(Berlin).Lat cities(Athens).Lat]
lon = [cities(Paris).Lon cities(London).Lon...
       cities(Rome).Lon cities(Madrid).Lon...
       cities(Berlin).Lon cities(Athens).Lon]

lat =
   48.8708   51.5188   41.9260   40.4312   52.4257   38.0164
lon =
    2.4131   -0.1300   12.4951   -3.6788   13.0802   23.5183
latstd =
lonstd =

Version History

Introduced before R2006a