Gives the date corresponding to the number of days since January 1, 1900.

Required Arguments

NDAYS — Number of days since January 1, 1900.   (Input)

IDAY — Day of the input date.   (Output)

MONTH — Month of the input date.   (Output)

IYEAR — Year of the input date.   (Output)
1950 would correspond to the year 195 A.D. and −50 would correspond to year 50 B.C.

FORTRAN 90 Interface

Generic:                              CALL NDYIN (NDAYS, IDAY, MONTH, IYEAR)

Specific:                             The specific interface name is NDYIN.

FORTRAN 77 Interface

Single:                                CALL NDYIN (NDAYS, IDAY, MONTH, IYEAR)

Description

Routine NDYIN computes the date corresponding to the number of days since January 1, 1900. For an input value of NDAYS that is negative, the date computed is prior to January 1, 1900. The routine NDYIN is the inverse of NDAYS.

Comments

The beginning of the Gregorian calendar was the first day after October 4, 1582, which became October 15, 1582. Prior to that, the Julian calendar was in use. Routine NDYIN makes the proper adjustment for the change in calendars.

Example

The following example uses NDYIN to compute the date for the 100th day of 1986. This is accomplished by first using  NDAYS to get the “day number” for December 31, 1985.

 

      USE NDYIN_INT

      USE NDAYS_INT

      USE UMACH_INT

 

      IMPLICIT   NONE

      INTEGER    IDAY, IYEAR, MONTH, NDAYO, NOUT, NDAY0

!

      NDAY0 = NDAYS(31,12,1985)

      CALL NDYIN (NDAY0+100, IDAY, MONTH, IYEAR)

      CALL UMACH (2, NOUT)

      WRITE (NOUT,*) 'Day 100 of 1986 is (day-month-year) ', IDAY, &

                   '-', MONTH, '-', IYEAR

      END

Output

 

Day 100 of 1986 is (day-month-year)   10-  4-  1986

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