GreatCircle Application for the Palm OS
GreatCircle is an application for Palm OS based handhelds to compute the great circle distance
between two locations on the Earth. It also displays the great circle bearing angle from one
location to the other.
GreatCircle can be used in conjunction with the GeoDB database application.
You can think of GreatCircle as the computation engine and GeoDB holds the location information.
However, as of Version 2.0, you can input locations manually.
If you do not have GeoDB installed in your handheld you may also want to install the GeoDB
application available here
GreatCircle displays the following data:
- Latitude and longitude of two Earth locations -- selected from the GeoDB database
- The great circle distance between the locations in either: kilometers, nautical miles,
miles, meters or feet.
- The great circle bearing angle from the 'From' locations to the 'To' location.
We hope you find GreatCircle a useful adjunct to your Palm applications.
The gc20.zip archive file includes:
To install GreatCircle open the gc20.zip file and use your Palm installer to install
- The executable file to be installed in your Palm.
- The required mathematics library -- V1.1
- This file -- gc.html
- gcmain.gif, gcmenu1.gif, gcmenu2.gif, gcmenu3.gif, gcempty.gif
- Images for gc.html
Great Circle requires the included MathLib.prc*.
If you already have MathLib.prc installed you do not need to install it.
If you do not have GeoDB you should install it. It will make input of location data much
easier. To do this download
the geodb.html documentation with your internet browser and install GeoDB accordingly.
The included MathLib.prc is the latest version (V1.1 dated 4/14/1999). You may update with
this one if you desire.
GreatCircle will be placed in the 'unfiled' category. You may move it to any category.
Using the Application
When you first open GreatCircle the main screen has no data locations defined.
You will see four data headings as shown on the right. You will also see the name of the active
GeoDB database in the upper right (if you have installed it).
Once both the 'From:' and 'To:' locations are defined, the distance and bearing are computed.
Other controls are available in the 'Data' and 'Units' menus, discussed next.
The two items are:
- Database: This menu item allows you to open another database currently installed in
Palm OS memory.
Tapping Database pops up a dialog box to cycle through all of GeoDB's installed
databases. Once a database is Opened the current database is closed (but not
deleted) and the opened one becomes active.
- Pen: This menu item allows you to manually enter data for a location.
- Decimal Digits: This menu item allows you to select the number of decimal digits to
be displayed for the distance and bearing.
- About -- The About menu tells you the current version number, the build number, and a
brief description of GreatCircle.
Future releases will change the version number only
for major changes. All changes will have an increasing Bld: (build) number.
sure that your version is up-to-date check the Bld: number.
The units choices are:
Tapping the desired unit name will immediately return to the main display with the data in
the selected unit.
- Kilometers -- Display distance in kilometers (km).
- Naut. Miles -- Display distance in nautical miles (nm).
- Miles -- Display distance in statute miles (mi).
- Meters -- Display distance in meters (m).
- Feet -- Display distance in feet (ft).
- Degrees -- Display great circle bearing angle in degrees.
- Grads -- Display great circle bearing angle in grads (grads).
(There are 100 grads and 90 degrees in a right angle.)
GreatCircle was created by
David W. Bray, Potsdam, NY;
Copyright © 1999-2004 David W. Bray, All Rights Reserved.
The Bray Palm OS Page can be found at:
GreatCircle is freeware no registration is required. We hope you enjoy using it.
This archive may be freely redistributed, provided it is made available only in its complete,
unmodified form with no additional files and for noncommercial purposes only.
Any other use must have prior written authorization from
David W. Bray.
Unauthorized commercial use includes, but is not limited to:
- GreatCircle itself as a product for sale.
- Accompanying a magazine, book or other publication for sale.
- Distribution with 'Media', 'Copying' or other incidental costs.
- Available for download with access or download fees.
This program is provided without warranty and the user accepts full responsibility for
any damages, direct, indirect, incidental, consequential, special or
exemplary damages or lost profit resulting from any use or misuse of this application.
* Many thanks to Rick Huebner, the author of MathLib, for his excellent routines and
making them freely available.
*Program Changes in Version 2.0
Version 1.2 Bld:307 is the original release.
Future releases will change the version number only for major changes. All changes will have an
increasing Bld: (build) number.
- Added dummy button for refresh in OS5 (V1.2 Bld:308)
- Added 'Find' button (V1.2 Bld:309)
- Added 'Database' menu item to allow selection of GeoDB databases. (V1.3 Bld:315)
- Changes to improve OS4 compatibility (V1.3 Bld:316)
- Changed internal data structure to allow From/To locations to be in different databases.
- Changed the algorithm for more accuracy, thereby allowing very small distances to be
displayed. (V2.0 Bld:404)
- Added "Pen" (manual) location input. (V2.0 Bld:404)
- Added Feet, and Meters to the Units menu. (V2.0 Bld:404)
- Added selection of result precision. (V2.0 Bld:404)
To be sure that your version is up-to-date a check the Bld: number shown in the 'About'
The current Bld: is 404.