1       REM
2       REM     Handling program for JULDAY
3       REM
5       DIM FLAG(1)
10      FLAG(0)=1 : PRINT
15      PRINT "Calendar date to Julian days"
20      FLAG(1)=0 : PRINT
25      INPUT "Calendar date (D,M,Y)"; DY,MN,YR
30      GOSUB 1100 : JD=DJD+2415020!
35      PRINT "J days since 1900 Jan 0.5: ";DJD
40      PRINT "Julian date..............: "; JD
44      PRINT : INPUT "Again (Y or N) "; AN$
50      IF AN$="Y" THEN GOTO 20
55      STOP
1097    REM
1098    REM     Subroutine JULDAY
1099    REM
1100    IF FLAG(1)=1 THEN RETURN
1105    DEF FNITG(W)=INT(W)+FLAG(0)*SGN(W)*INT((SGN(W)-1)/2)
1110    MN1=MN : YR1=YR : FLAG(1)=1 : B=0
1115    IF YR1<0 THEN YR1=YR1+1
1120    IF MN<3 THEN MN1=MN+12 : YR1=YR1-1
1125    IF YR<1582 THEN GOTO 1145
1130    IF YR=1582 AND MN<10 THEN GOTO 1145
1135    IF YR=1582 AND MN=10 AND DY<15 THEN GOTO 1145
1140    A=INT(YR1/100) : B=2-A+INT(A/4)
1145    IF YR1<0 THEN GOTO 1155
1150    C=INT(365.25*YR1)-694025! : GOTO 1160
1155    C=FNITG((365.25*YR1)-.75)-694025!
1160    D=INT(30.6001*(MN1+1))
1165    DJD=B+C+D+DY-.5
1170    RETURN