1 files changed, 74 insertions, 0 deletions
diff --git a/src/libcf/saa.c b/src/libcf/saa.c
new file mode 100644
index 0000000..0d2d0e3
--- /dev/null
+++ b/src/libcf/saa.c
@@ -0,0 +1,74 @@
+/*****************************************************************************
+ *              Johns Hopkins University
+ *              Center For Astrophysical Sciences
+ *              FUSE
+ *****************************************************************************
+ *
+ * Synopsis:    int saa(saareg *saa, double lon, double lat)
+ *
+ * Description: Determines if FUSE is in the SAA for given models of the SAA
+ *              
+ *
+ * Arguments:   saareg *saa           A structure containing data that roughly
+ *                                    outlines the SAA region.
+ *                                    (n_points: number of points
+ *                                     lat:    the latitude array
+ *                                     lon: the longitude array)
+ *                                    (currently we have only one model).
+ *              double lon,lat        Geocentric longitude and latitude of FUSE
+ *
+ * Returns:     int                   0 if not in SAA
+ *                                    1 if in SAA
+ *                    
+ * History:     07/17/98  E. Murphy   Begin work.
+ *              06/22/99        peb   Tidied code, added FITS_ wrappers,
+ *                                    removed hardcoded variables.
+ *              07/02/99        peb   Moved SAA data to a structure.
+ *              08/25/99        emm   Fixed bug in setting maxlon
+ *              08/28/03 v1.3   bjg   Adopt Bryce's algorithm for determining
+ *					when FUSE is in the SAA.
+ *              08/28/03 v1.4   bjg   v1.3 didn't compile but v1.4 does
+ *              08/29/03 v1.5   bjg   slightly modified getDir
+ *
+ ****************************************************************************/
+ 
+#include "calfuse.h"
+
+int getDir(double lon0,double lat0,double lon1,double lat1,double lon2,double lat2)
+{
+
+double dx1, dx2, dy1, dy2, t1, t2;
+    
+  dx1=lon1-lon0; dy1=lat1-lat0;
+  dx2=lon2-lon0; dy2=lat2-lat0;
+
+  t1=dx1*dy2; t2=dy1*dx2;
+
+  if (t1>t2) 
+    return(-1);
+  if (t1<t2) 
+    return(1);
+  
+
+  return(1);
+
+}
+
+
+int
+saa(saareg *saa, double lon, double lat)
+{
+int i;
+int dir=0;
+int oldDir=0;
+
+for (i=0; i<saa->n_points-1; i++) {
+    dir=getDir(lon,lat,(double)(saa->lon[i]),(double)(saa->lat[i]),(double)(saa->lon[i+1]),(double)(saa->lat[i+1]));
+    if (dir*oldDir<0)
+      return(0);
+    else
+      oldDir=dir;
+    }
+    
+  return(1);
+}