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authorKatolaZ <katolaz@freaknet.org>2022-10-06 11:38:17 +0100
committerKatolaZ <katolaz@freaknet.org>2022-10-06 11:38:17 +0100
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gridcal -- compute the great-circle distance between two grid locators
======================================================================
-`gridcal` computed the short-path great-circle distance between two grid
+`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
+
+With two locators 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.
+
+