function dd1 = ddate(date1); 
% copied from ddate.g, translated to matlab.
% return decimal years */
% input: date1 format yyymmdd
% output: date in decimal years */

    y1 = floor(date1/10000);
    m1 = floor(date1/100)-100*y1;
    d1 = date1-10000*y1-100*m1;
    dd1 = y1+(m1-1)/12+d1/365;
    return;