**Geodesic Lines of the Revolution Ellipsoid (**
Spanish version**)**

**Program objectives**

This computer program has been developed to calculate the geodesic lines of the revolution
ellipsoid, defined by the Geodetic Reference System of 1980 (GRS80). The geodesic lines are
computed for two points over this ellipsoid. The *distance* and the *azimuth* for
each geodesic are also computed. The distance between the two points that define this geodesic,
is computed along this path. The azimuth is also computed for these two points as the angle,
measured from North and clockwise, between the meridian passing by the first point and the
geodesic, which connects the first and the second points.

**Program description**

The *geodesic* program is enclosed into a ZIP file named
"geodesic.zip".
When you have got the ZIP file and you have uncompressed this file, you have the files named
**geodesic.exe** and **input.dat**. The file **geodesic.exe** contains a program (in
FORTRAN code for PC) to calculate the geodesic lines, for two points over the revolution
ellipsoid, defined by the Geodetic Reference System of 1980 (GRS80).
The file named **input.dat** is an ASCII file with the latitude and longitude of the
computation points. At the final of the computation, we obtain a new file named **output.dat**
which contains the distance (in km) and the azimuth (in degrees), for the geodesic lines that
connect the points listed in the file **input.dat**. These geodesic lines are enclosed into
the files named **geodesic_001.dat** to **geodesic_nnn.dat**, where *nnn* is the
number of the pairs of points enclosed in the file **input.dat**. The program also computes
the circle arc that connects the first and the second points of each pair of points, to compare
with the geodesic line. The circle arcs are enclosed into the files named
**circle_arc_001.dat** to **circle_arc_nnn.dat**, where *nnn* is the number of
the pairs of points enclosed in the file **input.dat**.
The file **input.dat** has the format:

LAT1, LONG1, LAT2, LONG2

. . . . . . . . . . .

. . . . . . . . . . .

. . . . . . . . . . .

LAT1, LONG1 = Geographical coordinates of the first point of the pair, latitude in degrees
(north positive) and longitude in degrees (east positive).

LAT2, LONG2 = Geographical coordinates of the second point of the pair, latitude in degrees
(north positive) and longitude in degrees (east positive).