Simple tesseroid model

The files in the folder cookbook/simple_tess show how to calculate the gravitational fields of a simple 2 tesseroid model at 260 km height.

For this simple setup, the model file looks like this:

# Test tesseroid model file
10 20 10 20 0 -50000 200
-20 -10 -20 -10 0 -30000 -500

The simple_tess.sh script performs the calculations and calls the plot.py script to plot the results:

#!/bin/bash

# Generate a regular grid, pipe it to all the computation programs,
# and write the result to output.txt

tessgrd -r-45/45/-45/45 -b101/101 -z260e03 | \
tesspot model.txt | \
tessgx model.txt | tessgy model.txt | tessgz model.txt | \
tessgxx model.txt  | tessgxy model.txt  | \
tessgxz model.txt  | tessgyy model.txt  | \
tessgyz model.txt  | tessgzz model.txt -v -llog.txt > output.txt

# Make a plot with the columns of output.txt
python plot.py output.txt 101 101

tessgrd generates a regular grid and prints that to standard output (stdout). The scripts pipes the grid points to tesspot etc. to calculate the corresponding fields. Option -v tells tessgzz to print information messages (to stderr). Option -llog.txt tells tessgzz to log the information plus debug messages to a file called log.txt.

The columns of the output file will be, respectively: longitude, latitude, height, potential, gx, gy, gz, gxx, gxy, gxz, gyy, gyz, and gzz. The result should look like this (“column” means the column of the output file):

Plot of the columns of output.txt generated by simple_tess.sh. Orthographic projection (thanks to the Basemap toolkit of matplotlib).