GreatCircle Application for Palm OS

GreatCircle Application for the Palm OS
Version 1.3^*

Description

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 only be used in conjunction with the GeoDB database application. GreatCircle is the computation engine and GeoDB holds the location information.

If you do not have GeoDB installed in your handheld you must also install the GeoDB application available here http://www.40-below.com/palm/geodb11.zip.

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, or miles.
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.

Installation

gc13.prc: The executable file to be installed in your Palm.
MathLib.prc: The required mathematics library -- V1.1
gc.html: This file -- gc.html
gcmain.gif, gcmenu1.gif, gcmenu2.gif, gcmenu3.gif, gcempty.gif: Images for gc.html

To install open the gc13.zip file and use your Palm installer to install gc13.prc.
Great Circle requires GeoDB and MathLib.prc^*.
If you already have MathLib.prc installed you do not need to install it.
If you do not have GeoDB you must install it. To do this download http://www.40-below.com/palm/geodb11.zip, read 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.

GreatCircle empty main display

Using the Program

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.

From: This heading is also a button to open a new page containing the GeoDB database so that you can select the 'From' location.
Selection is done simply by scrolling to the desired location and tapping its name to highlight it. Then tapping the 'Select' button.
The display will then switch back to the main GreatCircle page and the location data will be filled.
If you exit the GeoDB page without selecting a record the previously selected location is retained.
You may use the Open menu (discussed below) to select the desired database before making the From or To selections.
To: This heading is also a button which functions exactly as the 'From' heading button except it fills the 'To' latitude and longitude.
Distance: This is the distance between the 'From' and 'To' locations in the desire units.
Bearing: This is the great circle bearing angle between the 'From' and 'To' locations, respectively, in the desire units. North is 0 degrees and rotates clockwise. East is 90 degrees (100 grads), etc.

Once both the 'From:' and 'To:' locations are filled, the distance and bearing are computed.

Other controls are available in the 'Commands' and 'Units' menus, discussed next.

Commands Menu

The two items are:

Open: This menu item allows you to open another database currently installed in Palm OS memory.
Tapping Open pops up a dialog box to cycle through all of GeoDB's installed databases. Once one is Opened the current database is closed (but not deleted) and the opened one becomes active.
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.
To be sure that your version is up-to-date check the Bld: number.

Units Menu

The units choices are:

Kilometers -- Display distance in kilometers (km).
Naut. Miles -- Display distance in nautical miles (nm).
Miles -- Display distance in statute miles (mi).
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.)

Tapping the desired unit name will immediately return to the main display with the data in the selected unit.

Contact Info

GreatCircle was created by David W. Bray, Potsdam, NY;
Copyright © David W. Bray 2002-2003, All Rights Reserved.
The author may be contacted at: bray@davidbray.org

The Bray Palm OS Page can be found at: http://www.40-below.com/palm/

Registering

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 at bray@davidbray.org

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.

Disclaimer

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.

Foot Notes

^* Many thanks to Rick Huebner, the author of MathLib, for his excellent routines and making them freely available.

^*Program Changes in Version 1.3

Version 1.3 Bld:307 is the original release.

Added dummy button for refresh in OS5 (V1.3 Bld:308)
Added 'Open' 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. (V1.3 Bld:331)

Future releases will change the version number only for major changes. All changes will have an increasing Bld: (build) number.
To be sure that your version is up-to-date a check the Bld: number shown in the 'About' screen.

The current Bld: is 331.