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Astronomy program doesn't work

Marcial (18)
Hello, fellows, how are you?
I'm little less than a beginner in C++, but I'd like to know why this code, which supposedly would give me the time of moon transit, isn't working. It returns to me these erros:

[Linker error] undefined reference to `fill_planet_data(planet_data*, int, double, double, double, char const*)'
[Linker error] undefined reference to `dmy_to_day@16'
[Linker error] undefined reference to `dmy_to_day@16'
[Linker error] undefined reference to `load_file_into_memory(char const*, unsigned int*)'
[Linker error] undefined reference to `WinMain@16'
ld returned 1 exit status

I've barely passed in the programming discipline at college, and that only because of my friends' help. Now I'm looking for programs that attend my personal interests, but I'm getting frustrated as every code I get has some problem. Can you please help me? By the way, this code is from Project Pluto (http://www.projectpluto.com/source.htm) and I couldn't find their forum, nor did their FAQ help me, that's why I'm asking here. I hope you don't mind.

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#include <time.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "watdefs.h"
#include "lunar.h"
#include "date.h"
#include "afuncs.h"
#include "riseset3.h"

const static double pi =
     3.1415926535897932384626433832795028841971693993751058209749445923078;

static double look_for_transit_time( const int planet_no,
                  double jd,
                  const double observer_lat, const double observer_lon,
                  const char *vsop_data, const int real_transit)
{
   int iterations = 10;
   double delta = 1.;

   do
      {
      PLANET_DATA pdata;

      fill_planet_data( &pdata, planet_no, jd,
                          observer_lat, observer_lon, vsop_data);

      delta = atan2( pdata.altaz_loc[1], pdata.altaz_loc[0]);
      if( !real_transit)
         delta += pi;
      while( delta < -pi)
         delta += pi + pi;
      while( delta > pi)
         delta -= pi + pi;
      if( planet_no == 10)       /* moon moves a little faster */
         delta *= 30.5 / 29.5;
      delta *= sqrt( 1. - pdata.altaz_loc[2] * pdata.altaz_loc[2]);
      jd += delta / (2. * pi);
      }
      while( fabs( delta) > .0001 && iterations--);
   return( jd);
}

/* 2006 and before:  US Daylight "Saving" Time changes are on the
first Sunday in April,  last Sun in October.
   2007 and later:  second Sunday in March,  first Sunday in November. */

static int is_dst( const int minutes, const int day_of_year, const int year)
{
   int rval = 0;
   const int day1 = year + year / 4 - year / 100 + year / 400;
   const int is_leap = !(year % 4) && (year % 100 || !(year % 400));
   int start_day,  end_day;

   if( year <= 2006)
      {
      start_day = 31 + 28 + is_leap + 31 + 7 - (day1 + 5) % 7 - 1;
      end_day = 31 + 28 + is_leap + 31 + 30 + 31 + 30 + 31 + 31 + 30 +
                      31 - (day1 + 2) % 7 - 1;
      }
   else
      {
      start_day = 31 + 28 + is_leap + 14 - (day1 + 2) % 7 - 1;
      end_day = 31 + 28 + is_leap + 31 + 30 + 31 + 30 + 31 + 31 + 30 +
                      31 + 7 - (day1 + 2) % 7 - 1;
      }

   if( day_of_year > start_day && day_of_year < end_day)
      rval = 1;
   if( day_of_year == start_day && minutes >= 120)        /* after 2 PM */
      rval = 1;
   if( day_of_year == end_day && minutes < 120)        /* before 2 AM */
      rval = 1;
   return( rval);
}

/* Finds the time of transit (if real_transit == 1) or of "anti-transit",
   when the moon is lowest in the sky (if real_transit == 0).  For example,

   get_lunar_transit_time( 2011, 7, 29, 44.01, -69.9, -5, 1, 1);

   would return the time of the lunar transit for 2011 July 29,  as seen
   from latitude +44.01, longitude -69.9 (Bowdoinham, Maine),  in zone -5
   (Eastern US Time),  with daylight "saving" time included,  and looking
   for the actual transit.

   Return values:

      -2.         The 'vsop.bin' file wasn't found.
      <0. or >=1. The event occurred slightly before or slightly after
                  that calendar day.  Lunar transits average about 25 hours
                  apart,  so this will happen about once a month for each
                  type of event.
      >=0 and <1. Fraction of a day when the event occurred.  Thus, 0=start
                  of day at midnight,  .25 = 6:00 AM,  .7 = 4:48 PM.  See
                  the 'format_hh_mm( )' function below.

      Limitations:
                  Daylight "Saving" Time throws sand in the works.  On the
                  change day in autumn,  the day is 25 hours long,  such that
                  you can have two transits in one day;  this code will find
                  only one of them.  Also,  in autumn,  times such as 2:33 are
                  not determinate;  they could be "2:33 before clocks were set
                  back" or "2:33 after clocks were set back".  This is very
                  rarely a problem,  but one should be aware of it.
*/

double get_lunar_transit_time( const int year, const int month,
   const int day, const double latitude, const double longitude,
   const int time_zone, const int dst, const int real_transit)
{
   const long jd0 = dmy_to_day( day, month, year, 0);
   const long day_of_year = jd0 - dmy_to_day( 1, 1, year, 0);
   double jd = (double)jd0;
   static char *vsop_data = NULL;
   int dst_hours = (dst ? is_dst( 720, day_of_year, year) : 0);

   if( !vsop_data)
      vsop_data = load_file_into_memory( "vsop.bin", NULL);
   if( !vsop_data)
      return( -2.);
   jd -= (double)time_zone / 24.;      /* convert local to UT */
   jd -= dst_hours / 24.;

   jd = look_for_transit_time( 10, jd,
            latitude * pi / 180., longitude * pi / 180.,
            vsop_data, real_transit);
   jd += (double)time_zone / 24.;      /* convert UT back to local */
   jd += dst_hours / 24.;
   return( jd - (double)jd0 + .5);
}

/* Given a "time" from 0 to 1,  referring to a fraction of a day, */
/* format_hh_mm( ) produces a time string in hours and minutes.   */
/* If the time is out of range -- as happens routinely with the   */
/* transit times -- the time is shown as "--:--".                 */

void format_hh_mm( char *buff, const double time)
{
   if( time < 0. || time >= 1.)
      strcpy( buff, "--:--");
   else
      {
      const int minutes = (int)( time * 24. * 60.);

      sprintf( buff, "%02d:%02d", minutes / 60, minutes % 60);
      }
}

int get_zip_code_data( const int zip_code, double *latitude,
      double *longitude, int *time_zone, int *use_dst,
      char *place_name)
{
   FILE *ifile = fopen( "zips5.txt", "rb");
   char buff[100];
   int rval = -1;

   if( !ifile)
      return( -2);
   while( rval && fgets( buff, sizeof( buff), ifile))
      if( atoi( buff) == zip_code)
         {
         *longitude = atof( buff + 22);
         *latitude = atof( buff + 11);
         *time_zone = atoi( buff + 35);
         *use_dst = atoi( buff + 39);
         if( place_name)
            {
            int i;

            for( i = 0; buff[i + 48] >= ' '; i++)
               place_name[i] = buff[i + 48];
            buff[8] = '\0';
                  /* Add on two-letter state abbr: */
            sprintf( place_name + i, ", %s", buff + 6);
            }
         rval = 0;
         }
   fclose( ifile);
   return( rval);
}
toum (353)
It's a linker error.
The program is made of several files. The compiler/linker can't guess which files are part of a project, so you have to provide their list.
Apparently you forgot to include some files in the list.
Marcial (18)
Thanks a lot, toum. But how can I provide the list? As I've said, I'm less than dummy in programming. Other codes in the same zipped file (there's a lot of different programs in the pack; the code I quoted is the lun_tran.cpp program) return simply

[Linked error] undefined reference to 'WinMain@16'
ld returned 1 exit status

Can this be solved more easily?
toum (353)
lun_tran.cpp is not a program by itself, it's just some code.
If you want to use it, you have to write a program for that.


Marcial (18)
So, I need to write a program that calls the code lun_tran.cpp (or anyother code from the pack), that's it? How do I do that? Is there a model?
toum (353)
You need to learn how to make a program with basic input and output, and understand the notion of functions.

I think the big comment in lun_tran.cpp is pretty clear about how you can use it :
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/* Finds the time of transit (if real_transit == 1) or of "anti-transit",
   when the moon is lowest in the sky (if real_transit == 0).  For example,

   get_lunar_transit_time( 2011, 7, 29, 44.01, -69.9, -5, 1, 1);

   would return the time of the lunar transit for 2011 July 29,  as seen
   from latitude +44.01, longitude -69.9 (Bowdoinham, Maine),  in zone -5
   (Eastern US Time),  with daylight "saving" time included,  and looking
   for the actual transit.

   Return values:

      -2.         The 'vsop.bin' file wasn't found.
      <0. or >=1. The event occurred slightly before or slightly after
                  that calendar day.  Lunar transits average about 25 hours
                  apart,  so this will happen about once a month for each
                  type of event.
      >=0 and <1. Fraction of a day when the event occurred.  Thus, 0=start
                  of day at midnight,  .25 = 6:00 AM,  .7 = 4:48 PM.  See
                  the 'format_hh_mm( )' function below.

      Limitations:
                  Daylight "Saving" Time throws sand in the works.  On the
                  change day in autumn,  the day is 25 hours long,  such that
                  you can have two transits in one day;  this code will find
                  only one of them.  Also,  in autumn,  times such as 2:33 are
                  not determinate;  they could be "2:33 before clocks were set
                  back" or "2:33 after clocks were set back".  This is very
                  rarely a problem,  but one should be aware of it.
*/
double get_lunar_transit_time( const int year, const int month,
   const int day, const double latitude, const double longitude,
   const int time_zone, const int dst, const int real_transit)
{ 
    ...
}

Last edited on
closed account (iAk3T05o)
If you consider yourself a dummy and you know how to use arrays then hmm
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