/* dates.c
********************************************************************************
* dates.c
*
* This set of functions handles conversions between calendar dates. Days are
* given as the number of elapsed days since January 1, 2000 UTC (referred to as
* J2000 below), with negative numbers referring to earlier dates.
*
* RL_INT4 Jul_DUTCofYMD(year, month, day)
* converts from year, month, day to days since J2000.
* void Jul_YMDofDUTC(dutc, year, month, day)
* converts from days since J2000 to year, month and day.
* void Jul_YDofDUTC(dutc, year, day)
* converts from days since J2000 to year and day-of-year.
* void Jul_Gregorian(year, month, day)
* sets the date at which the Gregorian calendar was adopted.
* RL_BOOL Jul_IsLeapYear(year)
* determines whether the given year is a leap year.
* RL_INT4 Jul_YearDays(year)
* returns the number of days in the given year.
* RL_INT4 Jul_MonthDays(year, month)
* returns the number of days in the given month.
* RL_INT4 Jul_DUTCofJDN(jdn)
* converts from Julian Date to days since J2000.
* RL_INT4 Jul_JDNofDUTC(dutc)
* converts from days since J2000 to Julian Date.
*
* Mark R. Showalter, PDS Ring-Moon Systems Node, December 1995
* Revised by MRS 6/98 to conform to RingLib naming conventions.
*******************************************************************************/
#include <stdio.h> /* just to define TRUE and FALSE */
#include "julian.h"
#include "fortran.h"
/***********************************************************
* Definitions
***********************************************************/
#define JD_OF_J2000 2451545 /* Julian Date of noon, J2000 */
/***********************************************************
* Static variables
***********************************************************/
static RL_INT4 gregorian_dutc = -152384; /* Default is October 15, 1582 */
static RL_INT4 gregorian_year = 1582;
static RL_INT4 gregorian_month = 10;
static RL_INT4 gregorian_day = 15;
/***********************************************************
* Prototypes of internal functions
***********************************************************/
static RL_INT4 Jul_JDNofGregYMD RL_PROTO((RL_INT4 year, RL_INT4 month,
RL_INT4 day));
static void Jul_GregYMDofJDN RL_PROTO((RL_INT4 jdn, RL_INT4 *year,
RL_INT4 *month, RL_INT4 *day));
static RL_INT4 Jul_JDNofJulYMD RL_PROTO((RL_INT4 year, RL_INT4 month,
RL_INT4 day));
static void Jul_JulYMDofJDN RL_PROTO((RL_INT4 jdn, RL_INT4 *year,
RL_INT4 *month, RL_INT4 *day));
static void Jul_FixYM RL_PROTO((RL_INT4 *year, RL_INT4 *month));
/*
********************************************************************************
* EXPORTED USER ROUTINES
********************************************************************************
*$ Component_name:
* Jul_DUTCofYMD (dates.c)
*$ Abstract:
* Returns the number of days relative to January 1, 2000 for a given date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* RL_INT4 Jul_DUTCofYMD(year, month, day)
* RL_INT4 year, month, day;
*$ Inputs:
* year year value.
* month month (typically but not necessarily 1-12).
* day day (typically but not necessarily 1-31).
*$ Outputs:
* none
*$ Returns:
* number of days elapsed since January 1, 2000. Negative values refer to
* earlier dates.
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the number of days relative to January 1, 2000
* for a given date.
*$ External_references:
* none
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 Jul_DUTCofYMD(year, month, day)
RL_INT4 year, month, day;
{
RL_BOOL isgreg;
/* Correct year & month ranges */
Jul_FixYM(&year, &month);
/* Determine which calendar to use */
if (year > gregorian_year) isgreg = TRUE;
else if (year < gregorian_year) isgreg = FALSE;
else {
if (month > gregorian_month) isgreg = TRUE;
else if (month < gregorian_month) isgreg = FALSE;
else isgreg = (day >= gregorian_day);
}
/* Calculate and return date */
if (isgreg) return Jul_JDNofGregYMD(year, month, day) - JD_OF_J2000;
else return Jul_JDNofJulYMD (year, month, day) - JD_OF_J2000;
}
/*
********************************************************************************
*$ Component_name:
* Jul_YMDofDUTC (dates.c)
*$ Abstract:
* Returns the calendar year, month and day for a day number relative to
* January 1, 2000 for a given date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* void Jul_YMDofDUTC(dutc, year, month, day)
* RL_INT4 dutc, *year, *month, *day;
*$ Inputs:
* dutc number of days relative to January 1, 2000.
*$ Outputs:
* year year value.
* month month (1-12).
* day day (1-31).
*$ Returns:
* none
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the calendar year, month and day for a day number
* relative to January 1, 2000.
*$ External_references:
* none
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
void Jul_YMDofDUTC(dutc, year, month, day)
RL_INT4 dutc, *year, *month, *day;
{
if (dutc >= gregorian_dutc)
Jul_GregYMDofJDN(dutc + JD_OF_J2000, year, month, day);
else
Jul_JulYMDofJDN (dutc + JD_OF_J2000, year, month, day);
}
/*
********************************************************************************
*$ Component_name:
* Jul_YDofDUTC (dates.c)
*$ Abstract:
* Returns the calendar year and day-of-year number for a day number
* relative to January 1, 2000 for a given date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* void Jul_YDofDUTC(dutc, year, doy)
* RL_INT4 dutc, *year, *doy;
*$ Inputs:
* dutc number of days relative to January 1, 2000.
*$ Outputs:
* year year value.
* doy day-of-year (1-366).
*$ Returns:
* none
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the calendar year and day-of-year for a day number
* relative to January 1, 2000.
*$ External_references:
* Jul_YMDofDUTC(), Jul_DUTCofYMD()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
void Jul_YDofDUTC(dutc, year, doy)
RL_INT4 dutc, *year, *doy;
{
RL_INT4 month, day;
Jul_YMDofDUTC(dutc, year, &month, &day);
*doy = dutc - Jul_DUTCofYMD(*year, 1, 1) + 1;
}
/*
********************************************************************************
*$ Component_name:
* Jul_Gregorian (dates.c)
*$ Abstract:
* Sets the date at which the Gregorian calendar was adopted.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* void Jul_Gregorian(year, month, day)
* RL_INT4 year, month, day;
*$ Inputs:
* year year value.
* month month value (typically but not necessarily 1-12).
* day day value (typically but not necessarily 1-31).
*
* Note that the year, month and day are given according to the Gregorian
* calendar.
*$ Outputs:
* none
*$ Returns:
* none
*$ Side_effects:
* Saves the Gregorian calendar start date in internal variables. It
* remains in effect until the next call to Jul_Gregorian().
*$ Detailed_description:
* This function sets the date at which the Gregorian calendar was adopted.
* The default value is October 15, 1582; however, the user may wish to
* change this value because some countries adopted the Gregorian calendar
* on later dates. It affects the behavior of Jul_DUTCofYMD(),
* Jul_YMDofDUTC(), Jul_YDofDUTC(), etc.
*$ External_references:
* none
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
void Jul_Gregorian(year, month, day)
RL_INT4 year, month, day;
{
RL_INT4 jd;
/* Correct year & month ranges */
Jul_FixYM(&year, &month);
/* Calculate Julian date */
jd = Jul_JDNofGregYMD(year, month, day);
/* Save static variables */
gregorian_dutc = jd - JD_OF_J2000;
Jul_GregYMDofJDN(jd, &gregorian_year, &gregorian_month, &gregorian_day);
}
/*
********************************************************************************
*$ Component_name:
* Jul_IsLeapYear (dates.c)
*$ Abstract:
* Determines whether the given year is a leap year.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* RL_BOOL Jul_IsLeapYear(year)
* RL_INT4 year;
*$ Inputs:
* year year value.
*$ Outputs:
* none
*$ Returns:
* TRUE if it is a leap year; FALSE if it is not.
*$ Side_effects:
* none
*$ Detailed_description:
* This function determines whether the given year is a leap year. It
* returns TRUE if it is a leap year or FALSE if it is not.
*$ External_references:
* Jul_DUTCofYMD()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_BOOL Jul_IsLeapYear(year)
RL_INT4 year;
{
return (Jul_DUTCofYMD(year,3,1) != Jul_DUTCofYMD(year,2,29));
}
/*
********************************************************************************
*$ Component_name:
* Jul_YearDays (dates.c)
*$ Abstract:
* Returns the number of days in a given year.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* RL_INT4 Jul_YearDays(year)
* RL_INT4 year;
*$ Inputs:
* year year value.
*$ Outputs:
* none
*$ Returns:
* number of days in the year.
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the number of days in a given year.
*$ External_references:
* Jul_DUTCofYMD()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 Jul_YearDays(year)
RL_INT4 year;
{
return Jul_DUTCofYMD(year,12,31) - Jul_DUTCofYMD(year,1,1) + 1;
}
/*
********************************************************************************
*$ Component_name:
* Jul_MonthDays (dates.c)
*$ Abstract:
* Returns the number of days in a given month.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* RL_INT4 Jul_YearDays(year)
* RL_INT4 year;
*$ Inputs:
* year year value.
* month month value (1-12).
*$ Outputs:
* none
*$ Returns:
* number of days in the month.
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the number of days in a given month.
*$ External_references:
* Jul_DUTCofYMD()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 Jul_MonthDays(year, month)
RL_INT4 year, month;
{
return Jul_DUTCofYMD(year,month+1,1) - Jul_DUTCofYMD(year,month,1);
}
/*
********************************************************************************
*$ Component_name:
* Jul_DUTCofJDN (dates.c)
*$ Abstract:
* Converts from Julian Date to days relative to January 1, 2000.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* RL_INT4 Jul_DUTCofJDN(jd)
* RL_INT4 jd;
*$ Inputs:
* jd Julian Date.
*$ Outputs:
* none
*$ Returns:
* day relative to January 1, 2000 on which the given Julian date begins
* at noon.
*$ Side_effects:
* none
*$ Detailed_description:
* This function converts from Julian Date to days relative to January 1,
* 2000. The Julian date returned begins at noon on the specified date.
*$ External_references:
* none
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 Jul_DUTCofJDN(jd)
RL_INT4 jd;
{
return jd - JD_OF_J2000;
}
/*
********************************************************************************
*$ Component_name:
* Jul_JDNofDUTC (dates.c)
*$ Abstract:
* Converts from day relative to January 1, 2000 to Julian Date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* C, PUBLIC
*$ Declarations:
* RL_INT4 Jul_JDNofDUTC(dutc)
* RL_INT4 dutc;
*$ Inputs:
* dutc days relative to January 1, 2000.
*$ Outputs:
* none
*$ Returns:
* Julian date at noon of the given day.
*$ Side_effects:
* none
*$ Detailed_description:
* This function converts from day relative to January 1, 2000 to Julian
* Date. The Julian Date returned is the one beginning at noon on the
* given day.
*$ External_references:
* none
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 Jul_JDNofDUTC(dutc)
RL_INT4 dutc;
{
return dutc + JD_OF_J2000;
}
/*
********************************************************************************
* INTERNAL FUNCTIONS
********************************************************************************
* RL_INT4 Jul_JDNofGregYMD(RL_INT4 year, RL_INT4 month, RL_INT4 day)
*
* This internal function returns the Julian Date that begins on noon of a given
* date in the Gregorian calendar. The algorithm is from p. 604 of
* Seidelman, P. K. 1992. Explanatory Supplement to the Astronomical
* Almanac. University Science Books, Mill Valley.
*
* Input:
* year year value.
* month month value (1-12).
* dutc day value (1-31).
*
* Return: Julian Date value.
*******************************************************************************/
static RL_INT4 Jul_JDNofGregYMD(year, month, day)
RL_INT4 year, month, day;
{
RL_INT4 temp;
/* temp = (month - 14)/12; */
temp = (month <= 2 ? -1:0);
return (1461*(year + 4800 + temp))/4
+ (367*(month - 2 - 12*temp))/12
- (3*((year + 4900 + temp)/100))/4 + day - 32075;
}
/*
********************************************************************************
* void Jul_GregYMDofJDN(RL_INT4 jd, RL_INT4 *year, RL_INT4 *month, RL_INT4 *day)
*
* This internal function calculates the year, month and day in the Gregorian
* calendar which a given Julian Date begins (at noon). The algorithm is from
* p. 604 of
* Seidelman, P. K. 1992. Explanatory Supplement to the Astronomical
* Almanac. University Science Books, Mill Valley.
*
* Input:
* jd Julian Date value.
*
* Output:
* *year year value.
* *month month value (1-12).
* *day day value (1-31).
*******************************************************************************/
static void Jul_GregYMDofJDN(jd, year, month, day)
RL_INT4 jd, *year, *month, *day;
{
RL_INT4 l, n, i, j, d, m, y;
l = jd + 68569;
n = (4*l) / 146097;
l = l - (146097*n + 3)/4;
i = (4000*(l+1))/1461001;
l = l - (1461*i)/4 + 31;
j = (80*l)/2447;
d = l - (2447*j)/80;
l = j/11;
m = j + 2 - 12*l;
y = 100*(n-49) + i + l;
*year = y;
*month = m;
*day = d;
}
/*
********************************************************************************
* RL_INT4 Jul_JDNofJulYMD(RL_INT4 year, RL_INT4 month, RL_INT4 day)
*
* This internal function returns the Julian Date that begins on noon of a given
* date in the Julian calendar. The algorithm is from p. 606 of
* Seidelman, P. K. 1992. Explanatory Supplement to the Astronomical
* Almanac. University Science Books, Mill Valley.
*
* Input:
* year year value.
* month month value (1-12).
* day day value (1-31).
*
* Return: Julian Date value.
*******************************************************************************/
static RL_INT4 Jul_JDNofJulYMD(year, month, day)
RL_INT4 year, month, day;
{
return 367*year
- (7*(year + 5001 + (month-9)/7))/4
+ (275*month)/9
+ day + 1729777;
}
/*
********************************************************************************
* void Jul_JulYMDofJDN(RL_INT4 jd, RL_INT4 *year, RL_INT4 *month, RL_INT4 *day)
*
* This internal function calculates the year, month and day in the Julian
* calendar on which a given Julian Date begins (at noon). The algorithm is from
* p. 606 of
* Seidelman, P. K. 1992. Explanatory Supplement to the Astronomical
* Almanac. University Science Books, Mill Valley.
*
* Input:
* jd Julian Date value.
*
* Output:
* *year year value.
* *month month value (1-12).
* *day day fvalue (1-31).
*******************************************************************************/
static void Jul_JulYMDofJDN(jd, year, month, day)
RL_INT4 jd, *year, *month, *day;
{
RL_INT4 j, k, l, n, d, i, m, y;
j = jd + 1402;
k = (j-1)/1461;
l = j - 1461*k;
n = (l-1)/365 - l/1461;
i = l - 365*n + 30;
j = (80*i)/2447;
d = i - (2447*j)/80;
i = j/11;
m = j + 2 - 12*i;
y = 4*k + n + i - 4716;
*year = y;
*month = m;
*day = d;
}
/*
********************************************************************************
* void Jul_FixYM(RL_INT4 *year, RL_INT4 *month)
*
* This internal function shifts year and month values into the proper range.
* The month value will be between 1 and 12.
*
* Input:
* *year, *month current year and month values.
*
* Output:
* *year, *month corrected year and month values.
*******************************************************************************/
static void Jul_FixYM(year, month)
RL_INT4 *year, *month;
{
RL_INT4 y, m, dyear;
y = *year;
m = *month;
/* Shift month into range 1-12 */
dyear = (m-1) / 12;
m -= 12 * dyear;
y += dyear;
if (m < 1) {
m += 12;
y -= 1;
}
*year = y;
*month = m;
}
/*
********************************************************************************
* FORTRAN INTERFACE ROUTINES
********************************************************************************
*$ Component_name:
* FJul_DUTCofYMD (dates.c)
*$ Abstract:
* Returns the number of days relative to January 1, 2000 for a given date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* integer*4 function FJul_DUTCofYMD(year, month, day)
* integer*4 year, month, day
*$ Inputs:
* year year value.
* month month (typically but not necessarily 1-12).
* day day (typically but not necessarily 1-31).
*$ Outputs:
* none
*$ Returns:
* number of days elapsed since January 1, 2000. Negative values refer to
* earlier dates.
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the number of days relative to January 1, 2000
* for a given date.
*$ External_references:
* Jul_DUTCofYMD(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 FORTRAN_NAME(fjul_dutcofymd) (year, month, day)
RL_INT4 *year, *month, *day;
{
FORT_Init();
return Jul_DUTCofYMD(*year, *month, *day);
}
/*
********************************************************************************
*$ Component_name:
* FJul_YMDofDUTC (dates.c)
*$ Abstract:
* Returns the calendar year, month and day for a day number relative to
* January 1, 2000 for a given date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* subroutine FJul_YMDofDUTC(dutc, year, month, day)
* integer*4 dutc, year, month, day
*$ Inputs:
* dutc number of days relative to January 1, 2000.
*$ Outputs:
* year year value.
* month month (1-12).
* day day (1-31).
*$ Returns:
* none
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the calendar year, month and day for a day number
* relative to January 1, 2000.
*$ External_references:
* Jul_YMDofDUTC(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
void FORTRAN_NAME(fjul_ymdofdutc) (dutc, year, month, day)
RL_INT4 *dutc, *year, *month, *day;
{
FORT_Init();
Jul_YMDofDUTC(*dutc, year, month, day);
}
/*
********************************************************************************
*$ Component_name:
* FJul_YDofDUTC (dates.c)
*$ Abstract:
* Returns the calendar year and day-of-year number for a day number
* relative to January 1, 2000 for a given date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* subroutine FJul_YDofDUTC(dutc, year, doy)
* integer*4 dutc, year, doy
*$ Inputs:
* dutc number of days relative to January 1, 2000.
*$ Outputs:
* year year value.
* doy day-of-year (1-366).
*$ Returns:
* none
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the calendar year and day-of-year for a day number
* relative to January 1, 2000.
*$ External_references:
* Jul_YDofDUTC(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
void FORTRAN_NAME(fjul_ydofdutc) (dutc, year, day)
RL_INT4 *dutc, *year, *day;
{
FORT_Init();
Jul_YDofDUTC(*dutc, year, day);
}
/*
********************************************************************************
*$ Component_name:
* FJul_Gregorian (dates.c)
*$ Abstract:
* Sets the date at which the Gregorian calendar was adopted.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* subroutine FJul_Gregorian(year, month, day)
* integer*4 year, month, day
*$ Inputs:
* year year value.
* month month value (typically but not necessarily 1-12).
* day day value (typically but not necessarily 1-31).
*
* Note that the year, month and day are given according to the Gregorian
* calendar.
*$ Outputs:
* none
*$ Returns:
* none
*$ Side_effects:
* Saves the Gregorian calendar start date in internal variables. It
* remains in effect until the next call to Jul_Gregorian().
*$ Detailed_description:
* This function sets the date at which the Gregorian calendar was adopted.
* The default value is October 15, 1582; however, the user may wish to
* change this value because some countries adopted the Gregorian calendar
* on later dates. It affects the behavior of FJul_DUTCofYMD(),
* FJul_YMDofDUTC(), FJul_YDofDUTC(), etc.
*$ External_references:
* Jul_Gregorian(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
void FORTRAN_NAME(fjul_gregorian) (year, month, day)
RL_INT4 *year, *month, *day;
{
FORT_Init();
Jul_Gregorian(*year, *month, *day);
}
/*
********************************************************************************
*$ Component_name:
* FJul_IsLeapYear (dates.c)
*$ Abstract:
* Determines whether the given year is a leap year.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* logical*4 function FJul_IsLeapYear(year)
* integer*4 year
*$ Inputs:
* year year value.
*$ Outputs:
* none
*$ Returns:
* .TRUE. if it is a leap year; .FALSE. if it is not.
*$ Side_effects:
* none
*$ Detailed_description:
* This function determines whether the given year is a leap year. It
* returns .TRUE. if it is a leap year or .FALSE. if it is not.
*$ External_references:
* Jul_IsLeapYear(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_BOOL FORTRAN_NAME(fjul_isleapyear) (year)
RL_INT4 *year;
{
FORT_Init();
return (Jul_IsLeapYear(*year) ? FTRUE:FFALSE);
}
/*
********************************************************************************
*$ Component_name:
* FJul_YearDays (dates.c)
*$ Abstract:
* Returns the number of days in a given year.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* integer*4 function FJul_YearDays(year)
* integer*4 year
*$ Inputs:
* year year value.
*$ Outputs:
* none
*$ Returns:
* number of days in the year.
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the number of days in a given year.
*$ External_references:
* Jul_YearDays(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 FORTRAN_NAME(fjul_yeardays) (year)
RL_INT4 *year;
{
FORT_Init();
return Jul_YearDays(*year);
}
/*
********************************************************************************
*$ Component_name:
* FJul_MonthDays (dates.c)
*$ Abstract:
* Returns the number of days in a given month.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* integer*4 function FJul_YearDays(year)
* integer*4 year
*$ Inputs:
* year year value.
* month month value (1-12).
*$ Outputs:
* none
*$ Returns:
* number of days in the month.
*$ Side_effects:
* none
*$ Detailed_description:
* This function returns the number of days in a given month.
*$ External_references:
* Jul_MonthDays(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 FORTRAN_NAME(fjul_monthdays) (year, month)
RL_INT4 *year, *month;
{
FORT_Init();
return Jul_MonthDays(*year, *month);
}
/*
********************************************************************************
*$ Component_name:
* FJul_DUTCofJDN (dates.c)
*$ Abstract:
* Converts from Julian Date to days relative to January 1, 2000.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* integer*4 function FJul_DUTCofJDN(jd)
* integer*4 jd
*$ Inputs:
* jd Julian Date.
*$ Outputs:
* none
*$ Returns:
* day relative to January 1, 2000 on which the given Julian date begins
* at noon.
*$ Side_effects:
* none
*$ Detailed_description:
* This function converts from Julian Date to days relative to January 1,
* 2000. The Julian date returned begins at noon on the specified date.
*$ External_references:
* none
*$ Examples:
* Jul_DUTCofJDN(), FORT_Init()
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 FORTRAN_NAME(fjul_dutcofjdn) (jdn)
RL_INT4 *jdn;
{
FORT_Init();
return Jul_DUTCofJDN(*jdn);
}
/*
********************************************************************************
*$ Component_name:
* FJul_JDNofDUTC (dates.c)
*$ Abstract:
* Converts from day relative to January 1, 2000 to Julian Date.
*$ Keywords:
* JULIAN, TIME, CALENDAR
* FORTRAN, PUBLIC
*$ Declarations:
* integer*4 function FJul_JDNofDUTC(dutc)
* integer*4 dutc
*$ Inputs:
* dutc days relative to January 1, 2000.
*$ Outputs:
* none
*$ Returns:
* Julian date at noon of the given day.
*$ Side_effects:
* none
*$ Detailed_description:
* This function converts from day relative to January 1, 2000 to Julian
* Date. The Julian Date returned is the one beginning at noon on the
* given day.
*$ External_references:
* Jul_JDNofDUTC(), FORT_Init()
*$ Examples:
* none
*$ Error_handling:
* none
*$ Limitations:
* none
*$ Author_and_institution:
* Mark R. Showalter
* PDS Ring-Moon Systems Node
* NASA/Ames Research Center
*$ Version_and_date:
* 1.0: November 1995
*$ Change_history:
* none
*******************************************************************************/
RL_INT4 FORTRAN_NAME(fjul_jdnofdutc) (dutc)
RL_INT4 *dutc;
{
FORT_Init();
return Jul_JDNofDUTC(*dutc);
}
/*******************************************************************************
*/