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gridcal -- compute the great-circle distance between two grid locators
======================================================================
`gridcal` computes the short-path great-circle distance between two grid
locators. The Grid Locator System divides Earth into a series of
rectangles identified by a combination of letters and numbers, so that
the approximate position of a point can be expressed with a short
identifier like IO91vl.
Usage: gridcal <loc1> [<loc2> [<pwr>]]
If `gridcal` is given only one locator, it prints on output the latitude
and longitude of the centre of the corresponding grid square:
gridcal IO91vl
IO91vl 51.4792 -0.208333 0.898481 -0.0036361
The first two numbers are latitute and longitude in degree, the last two
are the corresponding values in radians.
With two locators provided as input, `gridcal` prints on output the two
locators and their great-circle distance, both in km and miles:
gridcal IO91vl JN65od
IO91vl JN65od 1213.71 754.164
If `gridcal` is given as third numerical argument, that number is
considered a "power" value in Watts, and `gridcal` will print on output
a longer line containing the two locators, the distance in km and miles,
the power value, and the corresponding km/W and miles/W:
gridcal IO91vl JN65od 1.2
IO91vl JN65od 1213.71 754.164 1.2 1011.42 628.47
The latter can be useful to check if a QSO with another ham radio
station qualifies for one of the thousand miles per Watt awards.
Dependencies
============
`gridcal` is written in ANSI C has no dependencies.
License
=======
`gridcal` is free software. It can be used, modified, distributed under
the terms of the ISC License. See the file LICENSE for more information.
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