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# Geo::Ellipsoids 0.14

Date Added: September 13, 2010  |  Visits: 658

Geo::Ellipsoids is a package for standard Geo:: ellipsoid a, b, f and 1/f values. SYNOPSIS use Geo::Ellipsoids; my \$obj = Geo::Ellipsoids->new(); \$obj->set(WGS84); #default print "a=", \$obj->a, "n"; print "b=", \$obj->b, "n"; print "f=", \$obj->f, "n"; print "i=", \$obj->i, "n"; print "e=", \$obj->e, "n"; print "n=", \$obj->n(45), "n"; CONSTRUCTOR new The new() constructor may be called with any parameter that is appropriate to the set method. my \$obj = Geo::Ellipsoid->new(); METHODS set Method sets the current ellipsoid. This method is called when the object is constructed (default is WGS84). \$obj->set(); #default WGS84 \$obj->set(Clarke 1866); #All built in ellipsoids are stored in meters \$obj->set({a=>1, b=>1}); #Custom Sphere 1 unit radius list Method returns a list of known elipsoid names. my @list=\$obj->list; my \$list=\$obj->list; while (@\$list) { print "\$_n"; } a Method returns the value of the semi-major axis. my \$a=\$obj->a; b Method returns the value of the semi-minor axis. my \$b=\$obj->b; #b=a(1-f) f Method returns the value of flatting my \$f=\$obj->f; #f=(a-b)/a i Method returns the value of the inverse flatting my \$i=\$obj->i; #i=1/f=a/(a-b) invf Method synonym for the i method my \$i=\$obj->invf; #i=1/f e Method returns the value of the first eccentricity, e. This is the eccentricity of the earths elliptical cross-section. my \$e=\$obj->e; e2 Method returns the value of eccentricity squared (e.g. e^2). This is not the second eccentricity, e or e-prime see the "ep" method. my \$e=sqrt(\$obj->e2); #e^2 = f(2-f) = 2f-f^2 = 1-b^2/a^2 ep Method returns the value of the second eccentricity, e or e-prime. The second eccentricity is related to the first eccentricity by the equation: 1=(1-e^2)(1+e^2). my \$ep=\$obj->ep; ep2 Method returns the square of value of second eccentricity, e (e-prime). This is more useful in almost all equations. my \$ep=sqrt(\$obj->ep2); #ep2=(ea/b)^2=e2/(1-e2)=a^2/b^2-1 n Method returns the value of n given latitude (degrees). Typically represented by the Greek letter nu, this is the radius of curvature of the ellipsoid perpendicular to the meridian plane. It is also the distance from the point in question to the polar axis, measured perpendicular to the ellipsoids surface. my \$n=\$obj->n(\$lat); Note: Some define a variable n as (a-b)/(a+b) this is not that variable. n_rad Method returns the value of n given latitude (radians). my \$n=\$obj->n_rad(\$lat); rho rho is the radius of curvature of the earth in the meridian plane. my \$rho=\$obj->rho(\$lat); rho_rad rho is the radius of curvature of the earth in the meridian plane. my \$rho=\$obj->rho_rad(\$lat); polar_circumference Method returns the value of the semi-minor axis times 2*PI. my \$polar_circumference=\$obj->polar_circumference; equatorial_circumference Method returns the value of the semi-major axis times 2*PI. my \$equatorial_circumference=\$obj->equatorial_circumference; shortname Method returns the shortname, which is the hash key, of the current ellipsoid my \$shortname=\$obj->shortname; longname Method returns the long name of the current ellipsoid my \$longname=\$obj->longname; data Method returns a hash reference for the ellipsoid definition data structure. my \$datastructure=\$obj->data; name2ref Method returns a hash reference (e.g. {a=>6378137,i=>298.257223563}) when passed a valid ellipsoid name (e.g. WGS84). my \$ref=\$obj->name2ref(WGS84).

 Requirements: No special requirements Platforms: Linux Keyword: Geoellipsoids,  Libraries,  Method,  Programming,  Radius Of Curvature,  Returns,  Value,  Value Of Users rating: 0/10