Function File: r = rcurve (spheroid, lat)

Function File: r = rcurve (type, spheroid, lat)

Function File: r = rcurve (…, angleUnit)

Return the length of a curve based on its type: meridian, parallel, or transverse.

Optional input argument type is one of "meridian", "parallel", or "transverse; default (when left empty or skipped) is "parallel". spheroid is the spheroid of choice (default: "wgs84"). lat is the latitude at which the curve length should be computed and can be a numeric scalar, vector or matrix. Output argument r will have the same size and dimension(s) as lat.

Optional input argument angleUnit can be either "radians" or "degrees" (= default); just "r" or "d" will do. All character input is case-insensitive.

Examples:

r = rcurve ("parallel", "wgs84", 45)
=> r =
4.5176e+06
Note: this is in meters

r = rcurve ("", 45)
=> r =
4.5176e+06

r = rcurve ("", "", 45)
=> r =
4.5176e+06

r = rcurve ("", "", pi/4, "radians")
=> r =
4.5176e+06

r = rcurve ("meridian", "wgs84", 45)
=> r =
6.3674e+06

r = rcurve ("transverse", "wgs84", 45)
=> r =
6.3888e+06

Also can use structures as inputs:

r = rcurve("", referenceEllipsoid ("venus"), 45)
=> r =
4.2793e+06

Package: mapping