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Merge branch 'master' of github.com:gergelypolonkai/swe-glib

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Gergely Polonkai 2013-09-14 16:32:00 +02:00
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# SWE-GLib # SWE-GLib
SWE-GLib is a GLib style wrapper library around the [Swiss Ephemeris library](http://www.astro.com/swisseph/), created by Astrodienst. SWE-GLib is a GLib style wrapper library around Astrodienst's [Swiss Ephemeris library](http://www.astro.com/swisseph/).
The source tree contains Astrodienst's (the writers/publishers of the Swiss Ephemeris library) ephemeride files, as requested by Alois Treindl of Astrodienst in a mail written to me on 24 July, 2013. The source tree contains Astrodienst's ephemeride files, as requested by Alois Treindl of Astrodienst in a mail written to me on 24 July, 2013.
## GTK-Doc ## GTK-Doc
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## Usage ## Usage
Many functions return non-opaque C structs; their documentation can be found inline, and in the generated GTK-Doc. Unless otherwise stated, the returned values should never be freed! Many functions return non-opaque C structs; their documentation can be found inline, and in the generated GTK-Doc. Unless otherwise stated, the returned values should never be freed.
### Initialization ### Initialization
@ -29,7 +29,7 @@ Then you need to create a `GsweTimestamp` object:
GsweTimestamp *timestamp = gswe_timestamp_new_from_gregorian_full(1983, 3, 7, 11, 54, 45, 0, 1.0); GsweTimestamp *timestamp = gswe_timestamp_new_from_gregorian_full(1983, 3, 7, 11, 54, 45, 0, 1.0);
``` ```
The `GsweTimetamp` object is used to convert dates between the Gregorian calendar dates and Julian Day values (not to be confused with Julian calendar dates!). The `GsweTimetamp` object is used to convert dates between the Gregorian calendar dates and Julian Day values (not to be confused with Julian calendar dates).
Next, you have to create a `GsweMoment` object: Next, you have to create a `GsweMoment` object:
@ -86,9 +86,26 @@ The Swiss Ephemeris library requires the altitude value to be specified for seve
> the altitude above sea must be in meters. Neglecting the altitude can result in an error of about 2 arc seconds with the moon and at an altitude 3000m. > the altitude above sea must be in meters. Neglecting the altitude can result in an error of about 2 arc seconds with the moon and at an altitude 3000m.
2 arc seconds is about 0.000555 degrees of error, which is, well, kind of small. Of course, if you need very precise horoscopes, precise horoscopes; otherwise, it is safe to pass any value (well, that seems logical. The average level of all dry lands is about 840 meters; the average level of the whole planet Earth (including oceans and seas) is around 280 meters). 2 arc seconds is about 0.000555 degrees of error, which is, well, kind of small. Of course, if you need very precise horoscopes or need planetary positions for a totally different thing, you should really provide a (close to) exact value; otherwise, it is safe to pass any value (well, which seems logical: the average level of all dry lands is about 840 meters; the average level of the whole planet Earth (including oceans and seas) is around 280 meters. Providing a value of ~400 should be OK most of the time).
## API stability ## API stability
The project is currently marked as 1.0. This means that API and ABI changes are very unlikely to happen. The project is currently marked as 1.0. This means that API and ABI changes are very unlikely to happen.
## Limitations
### Topocentric calculations only
Although the original Swiss Ephemeris library supports it, SWE-GLib can't do Heliocentric, nor Geocentric (as seen from the center of Earth) calculations, only Topocentric (as seen from a given point on Earth"s surface) calculations yet.
### Database size
The size of all data files provided by Astrodienst is around 40MB. Although it should not be a problem with today's home hardware, it can be a hard requirement on embedded systems. For basic calculations, keeping the following files under $(datadir)/swe-glib is usually enough:
* seas_18.se1
* semo_18.se1
* sepl_18.se1
### Fixed stars are not known yet
Although Swiss Ephemeris has the functionality to calculate the position of fixed stars, SWE-GLib doesn't provide such functionality. This, however, is a planned feature for the close future.