Newdate$= date$

mainloop:
DOW (Newdate$, weekday, day$) ' returns day of week as number and string
splitdate (Newdate$, day, month, year)
toJD (day, month, year, jd) ' returns Julien Day Number
print Newdate$;" "weekday;" ";day$ ;" - JD number: ";format$(jd,"%9.0f")

input "New Date: ", Newdate$
if Newdate$<>"" then goto mainloop

end

' given date as string, returns day, month, year
sub splitdate (currentdate$, d, m, y)
d= val(mid$(currentdate$,1,2))
m= val(mid$(currentdate$,4,2))
y= val(mid$(currentdate$,7,4))
end sub

'given day, month, year
'dayz=days since 1/1/1900 - agrees with Excel after 1/3/1900
sub toMSday (d, m, y, dayz, dayofyear)
dayofyear= d+int((m-1)*30.57+0.5)
if m>2 then
dayofyear= dayofyear-1
if (y mod 4)>0 then dayofyear= dayofyear-1
endif
dayz= int((y-1900)*365.25-0.25)+dayofyear+1
end sub

' given date as string, returns day of week as number and string
sub DOW (currentdate$,weekday, day$)
local d, m, y, dayz
splitdate (currentdate$, d, m, y)
toMSday (d, m, y, dayz, dayofyear)
weekday= abs((dayz-1) mod 7)
day$=mid$("SunMonTueWedThuFriSatSun",weekday*3+1,3)
end sub

' input day, month, year - returns julien day number
sub toJD ( d, m, y, jd)
ff = fix((m-14)/12)
jd = fix((1461*(y+4800+ff))/4)+fix((367*(m-2-12*ff))/12)-fix((3*( fix(y+4900+ff)/100))/4)+d-32075
end sub

'input julien day - returns day, month, year
sub fromJD (jd, d, m, y)
local l, n, i, j
l = jd + 68569
n = fix(( 4 * l ) / 146097)
l = l - fix(( 146097 * n + 3 ) / 4)
i = fix(( 4000 * ( l + 1 ) ) / 1461001)
l = l - fix(( 1461 * i ) / 4 )+ 31
j = fix(( 80 * l ) / 2447)
d = l - fix(( 2447 * j ) / 80)
l = fix(j / 11)
m = j + 2 - ( 12 * l )
y = 100 * ( n - 49 ) + i + l
end sub