;+ ; PRO overlay_map_vec ; ; :Description: ; Draw lines from a start point [lat0,lon0] with a direction [dlat,dlon] and arclength ; in degree on the plot window set up by sd_map_set. ; ; :Params: ; lat0: latitude of the start point [deg] ; lon0: longitude of the start point [deg] ; dlat: the latitudinal component of the vector to be drawn (positive: north) ; dlon: the longitudinal component of the vector to be drawn (positive: east) ; arclength: length of the vector in degree with which the vector is drawn. ; dlat and dlon are normalized by this value. Thus the absolute ; values of dlat and dlon are ignored. Only the ratio is concerned. ; ; :Keywords: ; linethick: Set a value of line thickness ; color: Set a value of color table with which the lines are drawn ; ; :Examples: ; ex) overlay_map_vec, 65., 270., 1.,-3, 18., linethick=1.5 ; ; :History: ; 2013/10/02: Initial release ; ; :Author: ; Tomo Hori (E-mail: horit at stelab.nagoya-u.ac.jp) ; ; $LastChangedBy: jwl $ ; $LastChangedDate: 2014-02-10 16:54:11 -0800 (Mon, 10 Feb 2014) $ ; $LastChangedRevision: 14265 $ ; $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/spdsoft/trunk/projects/erg/ground/radar/superdarn/overlay_map_vec.pro $ ;- ;- PRO overlay_map_vec, lat0, lon0, dlat, dlon, arclength, $ linethick=linethick, color=color ;Check the arguments npar = n_params() if npar ne 5 then return ;Calculate the end point of a vector with given arclength the0 = 90. - lat0 & dthe = (-1.)*dlat get_end_point_in_sph, the0,lon0,dthe,dlon,arclength, $ the1,phi1 lat1 = 90.-the1 & lon1 = phi1 ;Plot! plots, lon0,lat0, psym=4, symsize=1.2 plots, [lon0,lon1], [lat0,lat1], thick=linethick, color=color return end