MakeEllipseCoord()

Compute the coordinates of an ellipse placed at a given latitude and longitude.

Usage

coord = MakeEllipseCoord (lat, lon, dec, a_theta, b_theta, [cinterval])

Returns

coord :float, dimension(360/cinterval, 2)

The latitude [:,0] and longitude [:,1] coordinates of the ellipse in degrees.

Parameters

lat : float

The latitude of the center of the ellipse in degrees.

lon : float

The longitude of the center of the ellipse in degrees.

dec : float

Rotation angle of the semi-major axis of the ellipse in degrees with respect to local north.

a_theta : float

The angular radius of the semi-major axis of the ellipse in degrees.

b_theta : float

The angular radius of the semi-minor axis of the ellipse in degrees.

cinterval : optional, float, default = 1

Angular spacing in degrees of the output latitude and longitude points. If not present, the default is 1.

Description

MakeEllipseCoord will calculate the (lat, long) coordinates of an ellipse placed on a sphere at position (lat, lon). The semi-major and semi-minor axes, expressed in angular radii in degrees, are given by a_theta and b_theta, respectively. The semimajor axis of the ellipse is initially directed due north, and it is then rotated clockwise by the angle dec. This is useful for plotting ellipses on geographic maps. The first index in the output vectors corresponds to the northern rotated semimajor axis, and subsequent points are arranged in a clockwise manner. Input and output units are in degrees.