Mapping Toolbox

rcurve

Calculate radii of curvature on an ellipsoid

Syntax

• r = rcurve(geoid,lat)
  r = rcurve(geoid,lat,units)
  r = rcurve('parallel',geoid,lat,units)
  r = rcurve('meridian',geoid,lat,units)
  r = rcurve('transverse',geoid,lat,units)
  

Description

r = rcurve(geoid,lat) or r = rcurve('parallel',geoid,lat) returns the parallel radius of curvature at the latitude lat for a given elliptical definition, where geoid is a two-element geoid vector. This is the radius of the small circle encompassing the ellipsoid at the given latitude. The radius is a distance in units consistent with the semimajor axis, the first element of geoid.

r = rcurve(geoid,lat,units) specifies the units of the input lat, where units is any valid angle units string. The default is 'degrees'.

r = rcurve('meridian',geoid,lat,units) returns the meridianal radius, which is the radius of curvature at the latitude lat for the ellipse described by a meridian on the ellipsoid.

r = rcurve('transverse',geoid,lat,units) returns the transverse radius, which is the radius of a curve described by the intersection of the ellipsoid with a plane normal to the surface of the ellipsoid at the latitude lat.

Examples

The radii of curvature of the default geoid at 45º, in kilometers:

• r = rcurve('transverse',almanac('earth','geoid','km'),45,...
             'degrees')
  r =
     6.3888e+03
  
  r = rcurve('meridian',almanac('earth','geoid','km'),45,...
             'degrees')
  r =
     6.3674e+03
  
  r = rcurve('parallel',almanac('earth','geoid','km'),45,...
             'degrees')
  r =
     4.5024e+03
  

See Also

geod2aut iso2geod	Ellipsoid definition functions notation
rsphere	Radii of auxiliary spheres

rc2yx

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