Software for Grid Calculations

matlab

The following matlab routines convert between latitude and longitude and SOGLOBEC grid locations. The two routines getlatlon.m and getxy.m are short driver routines that convert a list of locations between grid and lat/lon. Included in these driver routines are some test locations and the correct conversions.

• getlatlon.m converts a list of grid locations (x,y) into the equivalent latitude and longitude. (calls grid2ll.m)
• getxy.m converts a list of latitude longitude pairs to the equivalent grid location. (calls ll2grid.m)
• grid2ll.m is the routine that converts from the SOGLOBEC grid location to true UTM and then to latitude and longitude.
• ll2grid.m is the routine that converts latitude and longitude to true UTM and then to the SOGLOBEC grid location.
• setuputm.m is a setup routine that is called only once. It defines the offset and rotation between the UTM coordinates and the SOGLOBEC grid. It also defines some parameters needed by the UTM <-> lat/lon routines.

FORTRAN

The following FORTRAN routines convert between latitude and longitude and the SOGLOBEC grid location. The first two routines (getlatlon.f and getxy.f) are main routines that read from standard input and write the answer to standard output. The other fortran files contain support subroutines. There is a Makefile for compiling and a c shell script to run tests of the software.

• getlatlon.f reads a station location (x.y) and converts to latitude and longitude. A series of locations can be put into a file which is read sequentially, e.g. getlatlon < loc.in > ll.out. (calls grid2ll.f).
• getxy.f reads a latitude and longitude pair from standard input and writes the grid location to standard output. A series of locations can be put into a file which is read sequentially, e.g. getxy < ll.in > loc.out. (calls ll2grid.f)
• maketest is a c shell script that tests both getlatlon and getxy using test input for which the answers are known. This script also checks for differences between the calculated answers and the expected answers. Due to slight differences in calculations, the last digit of the answer might be different by one.
• grid2ll.f converts from SOGLOBEC grid locations to latitude and longitude. (calls utm2ll.f)
• ll2grid.f converts from latitude and longitude to SOGLOBEC grid locations. (calls ll2utm.f)
• ll2utm.f is a routine that converts from latitude and longitude to true UTM.
• utm2ll.f converts a true UTM location to latitude and longitude.
• dtan.f is used in place of the builtin double precision tangent routine.
• Makefile is a make file to compile the two main routines.

Routines to create cruise track, stations and grid

• GMT script to create grid plots.
• GMT script to create station plots.
• perl scripts to convert longitude to the range 0 to 360 uplon and to the range -180 to 180 downlon .
• Supporting data files are in the Data directory and include only the GMT grid file with the ETOPO2 (8.2) bathymetry enhanced by the digitized stations from the charts.

Written by J. Klinck

February, 2001

Send questions or comments by e-mail to klinck@ccpo.odu.edu