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add julian day and modjulian day functions

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[SVN r16052]
This commit is contained in:
Jeff Garland
2002-11-02 17:38:06 +00:00
parent 2b5413b2ca
commit d0055e4c72
2 changed files with 61 additions and 6 deletions
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5
include/boost/date_time/gregorian_calendar.hpp
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@@ -29,7 +29,11 @@ namespace date_time {
static unsigned short day_of_week(const ymd_type& ymd);
//static unsigned short day_of_year(date_rep_type);
static date_int_type day_number(const ymd_type& ymd);
static date_int_type julian_day_number(const ymd_type& ymd);
static long modjulian_day_number(const ymd_type& ymd);
static ymd_type from_day_number(date_int_type);
static ymd_type from_julian_day_number(date_int_type);
static ymd_type from_modjulian_day_number(long);
static bool is_leap_year(year_type);
static unsigned short end_of_month_day(year_type y, month_type m);
static ymd_type epoch();
@@ -61,3 +65,4 @@ namespace date_time {
#endif

62
include/boost/date_time/gregorian_calendar.ipp
View File

@@ -13,7 +13,7 @@
namespace boost {
namespace date_time {
//! Return the day of the week (0==Sunday, 1==Monday, etc)
/*! Converts a the ymd_type into a day of the week number
/*! Converts a the year-month-day into a day of the week number
*/
template<typename ymd_type_, typename date_int_type_>
DATE_TIME_INLINE
@@ -42,13 +42,33 @@ namespace date_time {
unsigned long d = ymd.day + ((153*m + 2)/5) + 365*y + (y/4) - (y/100) + (y/400) - 32045;
return d;
}
//! Change a day number into a ymd_type structure
/*!
*
//! Convert a year-month-day into the julian day number
/*! Since this implementation uses julian day internally, this is the same as the day_number.
*/
template<typename ymd_type_, typename date_int_type_>
DATE_TIME_INLINE
date_int_type_
gregorian_calendar_base<ymd_type_,date_int_type_>::julian_day_number(const ymd_type& ymd)
{
return day_number(ymd);
}
//! Convert year-month-day into a modified julian day number
/*! The day number is an absolute number of days.
* MJD 0 thus started on 17 Nov 1858(Gregorian) at 00:00:00 UTC
*/
template<typename ymd_type_, typename date_int_type_>
DATE_TIME_INLINE
long
gregorian_calendar_base<ymd_type_,date_int_type_>::modjulian_day_number(const ymd_type& ymd)
{
return julian_day_number(ymd)-2400001; //prerounded
}
//! Change a day number into a year-month-day
template<typename ymd_type_, typename date_int_type_>
DATE_TIME_INLINE
ymd_type_
gregorian_calendar_base<ymd_type_,date_int_type_>::from_day_number(date_int_type dayNumber)
{
@@ -66,6 +86,35 @@ namespace date_time {
return ymd_type(year,month,day);
}
//! Change a day number into a year-month-day
template<typename ymd_type_, typename date_int_type_>
DATE_TIME_INLINE
ymd_type_
gregorian_calendar_base<ymd_type_,date_int_type_>::from_julian_day_number(date_int_type dayNumber)
{
date_int_type a = dayNumber + 32044;
date_int_type b = (4*a+3)/146097;
date_int_type c = a - ((146097*b)/4);
date_int_type d = (4*c + 3)/1461;
date_int_type e = c - ((1461*d)/4);
date_int_type m = (5*e + 2)/153;
unsigned short day = e - ((153*m + 2)/5) + 1;
unsigned short month = m + 3 - 12 * (m/10);
date_int_type year = 100*b + d - 4800 + (m/10);
//std::cout << year << "-" << month << "-" << day << "\n";
return ymd_type(year,month,day);
}
//! Change a modified julian day number into a year-month-day
template<typename ymd_type_, typename date_int_type_>
DATE_TIME_INLINE
ymd_type_
gregorian_calendar_base<ymd_type_,date_int_type_>::from_modjulian_day_number(long dayNumber)
{
date_int_type jd = dayNumber + 2400001; //is 2400000.5 prerounded
return from_julian_day_number(jd);
}
//! Determine if the provided year is a leap year
/*!
@@ -90,7 +139,6 @@ namespace date_time {
gregorian_calendar_base<ymd_type_,date_int_type_>::end_of_month_day(year_type year,
month_type month)
{
// switch (month.as_number()) {
switch (month) {
case 2:
if (is_leap_year(year)) {return 29;}
@@ -138,3 +186,5 @@ namespace date_time {
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/