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int usage(int retval, bool brief) {
if (brief)
( retval ? std::cerr : std::cout ) << "Usage:\n"
" RhumbSolve [ -i | -l lat1 lon1 azi12 ] [ -e a f ] [ -d | -: ] [ -f ] [\n"
" -p prec ] [ -s ] [ --comment-delimiter commentdelim ] [ --version | -h\n"
" | --help ] [ --input-file infile | --input-string instring ] [\n"
" --line-separator linesep ] [ --output-file outfile ]\n"
"\n"
"For full documentation type:\n"
" RhumbSolve --help\n"
"or visit:\n"
" http://geographiclib.sf.net/1.37/RhumbSolve.1.html\n";
else
( retval ? std::cerr : std::cout ) << "Man page:\n"
"NAME\n"
" RhumbSolve -- perform rhumb line calculations\n"
"\n"
"SYNOPSIS\n"
" RhumbSolve [ -i | -l lat1 lon1 azi12 ] [ -e a f ] [ -d | -: ] [ -f ] [\n"
" -p prec ] [ -s ] [ --comment-delimiter commentdelim ] [ --version | -h\n"
" | --help ] [ --input-file infile | --input-string instring ] [\n"
" --line-separator linesep ] [ --output-file outfile ]\n"
"\n"
"DESCRIPTION\n"
" The path with constant heading between two points on the ellipsoid at\n"
" (lat1, lon1) and (lat2, lon2) is called the rhumb line or loxodrome.\n"
" Its length is s12 and the rhumb line has a forward azimuth azi12 along\n"
" its length. A point at a pole is treated as a point a tiny distance\n"
" away from the pole on the given line of longitude. The longitude\n"
" becomes indeterminate when a rhumb line passes through a pole, and\n"
" RhumbSolve reports NaNs for the longitude in this case.\n"
"\n"
" NOTE: the rhumb line is not the shortest path between two points; that\n"
" is the geodesic and it is calculated by GeodSolve(1).\n"
"\n"
" RhumbSolve operates in one of three modes:\n"
"\n"
" 1. By default, RhumbSolve accepts lines on the standard input\n"
" containing lat1 lon1 azi12 s12 and prints lat2 lon2 on standard\n"
" output. This is the direct calculation.\n"
"\n"
" 2. Command line arguments -l lat1 lon1 azi12 specify a rhumb line.\n"
" RhumbSolve then accepts a sequence of s12 values (one per line) on\n"
" standard input and prints lat2 lon2 for each. This generates a\n"
" sequence of points on a rhumb line.\n"
"\n"
" 3. With the -i command line argument, RhumbSolve performs the inverse\n"
" calculation. It reads lines containing lat1 lon1 lat2 lon2 and\n"
" prints the values of azi12 s12 for the corresponding shortest rhumb\n"
" lines\n"
"\n"
"OPTIONS\n"
" -i perform an inverse calculation (see 3 above).\n"
"\n"
" -l line mode (see 2 above); generate a sequence of points along the\n"
" rhumb line specified by lat1 lon1 azi12.\n"
"\n"
" -e specify the ellipsoid via a f; the equatorial radius is a and the\n"
" flattening is f. Setting f = 0 results in a sphere. Specify f < 0\n"
" for a prolate ellipsoid. A simple fraction, e.g., 1/297, is\n"
" allowed for f. (Also, if f > 1, the flattening is set to 1/f.) By\n"
" default, the WGS84 ellipsoid is used, a = 6378137 m, f =\n"
" 1/298.257223563.\n"
"\n"
" -d output angles as degrees, minutes, seconds instead of decimal\n"
" degrees.\n"
"\n"
" -: like -d, except use : as a separator instead of the d, ', and \"\n"
" delimiters.\n"
"\n"
" -p set the output precision to prec (default 3); prec is the precision\n"
" relative to 1 m. See \"PRECISION\".\n"
"\n"
" -s By default, the rhumb line calculations are carried out exactly in\n"
" terms of elliptic integrals. This includes the use of the addition\n"
" theorem for elliptic integrals to compute the divided difference of\n"
" the isometric and rectifying latitudes. If -s is supplied this\n"
" divided difference is computed using Krueger series for the\n"
" transverse Mercator projection which is only accurate for |f| <\n"
" 0.01. See \"ACCURACY\".\n"
"\n"
" --comment-delimiter\n"
" set the comment delimiter to commentdelim (e.g., \"#\" or \"//\"). If\n"
" set, the input lines will be scanned for this delimiter and, if\n"
" found, the delimiter and the rest of the line will be removed prior\n"
" to processing and subsequently appended to the output line\n"
" (separated by a space).\n"
"\n"
" --version\n"
" print version and exit.\n"
"\n"
" -h print usage and exit.\n"
"\n"
" --help\n"
" print full documentation and exit.\n"
"\n"
" --input-file\n"
" read input from the file infile instead of from standard input; a\n"
" file name of \"-\" stands for standard input.\n"
"\n"
" --input-string\n"
" read input from the string instring instead of from standard input.\n"
" All occurrences of the line separator character (default is a\n"
" semicolon) in instring are converted to newlines before the reading\n"
" begins.\n"
"\n"
" --line-separator\n"
" set the line separator character to linesep. By default this is a\n"
" semicolon.\n"
"\n"
" --output-file\n"
" write output to the file outfile instead of to standard output; a\n"
" file name of \"-\" stands for standard output.\n"
"\n"
"INPUT\n"
" RhumbSolve measures all angles in degrees and all lengths (s12) in\n"
" meters. On input angles (latitude, longitude, azimuth) can be as\n"
" decimal degrees or degrees (d), minutes ('), seconds (\"). A decimal\n"
" point can only appear in the least significant component and the\n"
" designator (d, ', or \") for this component is optional; thus \"40d30\",\n"
" \"40d30'\", \"40.5d\", and 40.5 are all equivalent. By default, latitude\n"
" precedes longitude for each point; however on input either may be given\n"
" first by appending (or prepending) N or S to the latitude and E or W to\n"
" the longitude. Azimuths are measured clockwise from north; however\n"
" this may be overridden with E or W.\n"
"\n"
" See the \"QUOTING\" section of GeoConvert(1) for how to quote the DMS\n"
" designators ' and \".\n"
"\n"
"PRECISION\n"
" prec gives precision of the output with prec = 0 giving 1 m precision,\n"
" prec = 3 giving 1 mm precision, etc. prec is the number of digits\n"
" after the decimal point for lengths. For decimal degrees, the number\n"
" of digits after the decimal point is prec + 5. For DMS (degree,\n"
" minute, seconds) output, the number of digits after the decimal point\n"
" in the seconds component is prec + 1. The minimum value of prec is 0\n"
" and the maximum is 10.\n"
"\n"
"ERRORS\n"
" An illegal line of input will print an error message to standard output\n"
" beginning with \"ERROR:\" and causes RhumbSolve to return an exit code of\n"
" 1. However, an error does not cause RhumbSolve to terminate; following\n"
" lines will be converted.\n"
"\n"
"ACCURACY\n"
" The algorithm used by RhumbSolve uses exact formulas for converting\n"
" between the latitude, rectifying latitude (mu), and isometric latitude\n"
" (psi). These formulas are accurate for any value of the flattening.\n"
" The computation of rhumb lines involves the ratio (psi1 - psi2) / (mu1\n"
" - mu2) and this is subject to large round-off errors if lat1 is close\n"
" to lat2. So this ratio is computed using divided differences using one\n"
" of two methods: by default, this uses the addition theorem for elliptic\n"
" integrals (accurate for all values of f); however, with the -s options,\n"
" it is computed using the series expansions used by\n"
" TransverseMercatorProj(1) for the conversions between rectifying and\n"
" conformal latitudes (accurate for |f| < 0.01). For the WGS84\n"
" ellipsoid, the error is about 10 nanometers using either method.\n"
"\n"
"EXAMPLES\n"
" Route from JFK Airport to Singapore Changi Airport:\n"
"\n"
" echo 40:38:23N 073:46:44W 01:21:33N 103:59:22E |\n"
" RhumbSolve -i -: -p 0\n"
"\n"
" 103:34:58.2 18523563\n"
"\n"
" N.B. This is not the route typically taken by aircraft because it's\n"
" considerably longer than the geodesic given by GeodSolve(1).\n"
"\n"
" Waypoints on the route at intervals of 2000km:\n"
"\n"
" for ((i = 0; i <= 20; i += 2)); do echo ${i}000000;done |\n"
" RhumbSolve -l 40:38:23N 073:46:44W 103:34:58.2 -: -p 0\n"
"\n"
" 40:38:23.0N 073:46:44.0W\n"
" 36:24:30.3N 051:28:26.4W\n"
" 32:10:26.8N 030:20:57.3W\n"
" 27:56:13.2N 010:10:54.2W\n"
" 23:41:50.1N 009:12:45.5E\n"
" 19:27:18.7N 027:59:22.1E\n"
" 15:12:40.2N 046:17:01.1E\n"
" 10:57:55.9N 064:12:52.8E\n"
" 06:43:07.3N 081:53:28.8E\n"
" 02:28:16.2N 099:24:54.5E\n"
" 01:46:36.0S 116:52:59.7E\n"
"\n"
"SEE ALSO\n"
" GeoConvert(1), GeodSolve(1), TransverseMercatorProj(1).\n"
"\n"
"AUTHOR\n"
" RhumbSolve was written by Charles Karney.\n"
"\n"
"HISTORY\n"
" RhumbSolve was added to GeographicLib, <http://geographiclib.sf.net>,\n"
" in version 1.37.\n"
;
return retval;
}
|
