From ab6ee208e1a544fee6439e4ded07ac6690bf152a Mon Sep 17 00:00:00 2001 From: "Gergely POLONKAI (W00d5t0ck)" Date: Fri, 6 Sep 2013 12:12:43 +0200 Subject: [PATCH] Added a README.md file --- README.md | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 README.md diff --git a/README.md b/README.md new file mode 100644 index 0000000..bf45af9 --- /dev/null +++ b/README.md @@ -0,0 +1,39 @@ +# SWE-GLib + +SWE-GLib is a GLib style wrapper library around the [Swiss Ephemeris library](http://www.astro.com/swisseph/), created by Astrodienst. + +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. + +## Usage + +For exact calculations, you need to create a GsweTimestamp object: + +```c +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!). + +Next, you have to create a GsweMoment object: + +```c +GsweMoment *moment = gswe_moment_new_full(timestamp, 19.081599, 47.462485, 300.0, GSWE_HOUSE_PLACIDUS); +``` + +The GsweMoment object holds information of a given moment at a given place on earth. `gswe_moment_new_full()` requires a `GsweTimestamp` object, some geographical coordinates together with altitude above sea level (coordinates must be given in degrees, while altitude in meters!), and a house system to use. + +### About altitude + +The Swiss Ephemeris library requires the altitude value to be specified for several calculations. It also notifies how important it is: + +> 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). + +## API stability + +The project is currently marked as 1.0. However, without further notice, the API should not be seen as stable. + +This means that some function prototypes may be modified in the near future. Mostly error handling routines are missing, so some functions will get a `GError **` parameter. + +Otherwise, the API is final, in term of future compatibility. New functions may be added later, though.