- MakeEllipseCoord -
-
Compute coordinates of an ellipse placed at a given latitude and longitude.
- SUBROUTINE MakeEllipseCoord (
-
COORD, LAT, LON, DEC, A_THETA, B_THETA, CINTERVAL, CNUM )
- REAL*8
-
COORD(360/CINTERVAL, 2), LAT, LON, DEC, A_THETA, B_THETA
- REAL*8, OPTIONAL
-
CINTERVAL
- INTEGER, OPTIONAL
-
CNUM
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.
- COORD
-
(output) REAL*8, DIMENSION(360/CINTERVAL, 2)
The latitude (:,1) and longitude (:,2) coordinates of the ellipse in DEGREES. If not specified, CINTERVAL is assumed to 1.
- LAT
-
(input) REAL*8
The latitude of the center of the ellipse in DEGREES.
- LON
-
(input) REAL*8
The longitude of the center of the ellipse in DEGREES.
- DEC
-
(input) REAL*8
Rotation angle of the semi-major axis of the ellipse in DEGREES with respect to local north.
- A_THETA
-
(input) REAL*8
The angular radius of the semi-major axis of the ellipse in DEGREES.
- B_THETA
-
(input) REAL*8
The angular radius of the semi-minor axis of the ellipse in DEGREES.
- CINTERVAL
-
(input) REAL*8, OPTIONAL
Angular spacing in DEGREES of the output latitude and longitude points. If not present, the default is 1.
- CNUM
-
(output) INTEGER, OPTIONAL
Number of elements in the output arrays.
makecirclecoord(1)
Copyright 2012 by Mark Wieczorek <wieczor@ipgp.fr>.
This is free software; you can distribute and modify it under the terms of the revised BSD license.