Here's little program that establishes the name of day of week.
Give it a date and it tells you is it monday or friday etc..
enjoy
dim dayNames(6) as string
for i=0 to 6
read dayNames(i)
next i
data "sunday", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday"
print "Eternal Calendar"
print
input "day: ",day
input "mounth: ",mounth
input "year: ",year
if mounth < 3
dec year
inc mounth, 12
endif
d = year+int(year/4)-int(year/100)+int(year/400)+3*mounth-int((mounth+mounth+1)/5)+day+1
d = d-int(d/7)*7
print
print day;" . ";mounth;" . ";year;" is ";dayNames(d)
wait key