strf/rftime.c

92 lines
1.5 KiB
C

#include <stdio.h>
#include <math.h>
#include "rftime.h"
// nfd2mjd
double nfd2mjd(char *date)
{
int year,month,day,hour,min;
double mjd,dday;
float sec;
sscanf(date,"%04d-%02d-%02dT%02d:%02d:%f",&year,&month,&day,&hour,&min,&sec);
dday=day+hour/24.0+min/1440.0+sec/86400.0;
mjd=date2mjd(year,month,dday);
return mjd;
}
// Compute Julian Day from Date
double date2mjd(int year,int month,double day)
{
int a,b;
double jd;
if (month<3) {
year--;
month+=12;
}
a=floor(year/100.);
b=2.-a+floor(a/4.);
if (year<1582) b=0;
if (year==1582 && month<10) b=0;
if (year==1852 && month==10 && day<=4) b=0;
jd=floor(365.25*(year+4716))+floor(30.6001*(month+1))+day+b-1524.5;
return jd-2400000.5;
}
// Compute Date from Julian Day
void mjd2nfd(double mjd,char *nfd)
{
double f,jd,dday;
int z,alpha,a,b,c,d,e;
int year,month,day,hour,min;
float sec,x;
jd=mjd+2400000.5;
jd+=0.5;
z=floor(jd);
f=fmod(jd,1.);
if (z<2299161)
a=z;
else {
alpha=floor((z-1867216.25)/36524.25);
a=z+1+alpha-floor(alpha/4.);
}
b=a+1524;
c=floor((b-122.1)/365.25);
d=floor(365.25*c);
e=floor((b-d)/30.6001);
dday=b-d-floor(30.6001*e)+f;
if (e<14)
month=e-1;
else
month=e-13;
if (month>2)
year=c-4716;
else
year=c-4715;
day=(int) floor(dday);
x=24.0*(dday-day);
x=3600.*fabs(x);
sec=fmod(x,60.);
x=(x-sec)/60.;
min=fmod(x,60.);
x=(x-min)/60.;
hour=x;
sec=floor(1000.0*sec)/1000.0;
sprintf(nfd,"%04d-%02d-%02dT%02d:%02d:%06.3f",year,month,day,hour,min,sec);
return;
}