#include <math.h>

#define IGREG 2299161

void caldat(julian, mm, id, iyyy)
long julian;
int *mm, *id, *iyyy;
{
	long ja, jalpha, jb, jc, jd, je;

	if (julian >= IGREG) {
		jalpha = ((float) (julian-1867216) -0.25)/36524.25;
		ja = julian+1+jalpha-(long) (0.25*jalpha);
	} else
		ja = julian;
	jb = ja+1524;
	jc = 6680.0+((float) (jb-2439870)-122.1)/365.25;
	jd = 365*jc+(0.25*jc);
	je = (jb-jd)/30.6001;
	*id = jb-jd-(int) (30.6001*je);
	*mm = je-1;
	if (*mm > 12) *mm -= 12;
	*iyyy = jc-4715;
	if(*mm > 2) --(*iyyy);
	if(*iyyy <= 0) --(*iyyy);
}