function weekday=dayofweek(d)
% weekday=dayofweek([day month year])
% Uses Zeller's congruence to calculate the day of the
% week from the date
month=1+rem(d(2)+9,12);
year=d(3)-fix(month/11);
century=fix(year/100);
year=rem(year,100);
day=d(1);
val=fix(2.6*month-0.2)+day+year+fix(year/4)+fix(century/4)-2*century;
wday=1+rem(28+val,7);   % add 28 to ensure is a +ve value in 21st century
days=['Sunday   ';'Monday   ';'Tuesday  ';'Wednesday';'Thursday ';'Friday   ';'Saturday '];
weekday=days(wday,:);