function [gpsweek,sow,rollover]=jd2gps(jd);% JD2GPS  Converts Julian date to GPS week number (since%   1980.01.06) and seconds of week. Non-vectorized version.%   See also CAL2JD, DOY2JD, GPS2JD, JD2CAL, JD2DOW, JD2DOY,%   JD2YR, YR2JD.% Version: 28 Sep 03% Usage:   [gpsweek,sow,rollover]=jd2gps(jd)% Input:   jd       - Julian date% Output:  gpsweek  - GPS week number%          sow      - seconds of week since 0 hr, Sun.%          rollover - number of GPS week rolloversif nargin ~= 1  warning('Incorrect number of arguments');  return;endif jd < 0  warning('Julian date must be greater than or equal to zero');  return;endjdgps = cal2jd(1980,1,6);    % beginning of GPS week numberingnweek = fix((jd-jdgps)/7);sow = (jd - (jdgps+nweek*7)) * 3600*24;rollover = fix(nweek/1024);  % rollover every 1024 weeksgpsweek = mod(nweek,1024);