initial upload

lib/geometry.cpp

@@ -0,0 +1,48 @@
+/*
+Data structures for geometric elements and functions that operate on them.
+Defines the TESSEROID, SPHERE, and PRISM structures.
+*/
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+#include "constants.h"
+#include "logger.h"
+#include "geometry.h"
+
+
+/* Split a tesseroid into 8. */
+void split_tess(TESSEROID tess, TESSEROID *split)
+{
+    double dlon = 0.5*(tess.e - tess.w),
+           dlat = 0.5*(tess.n - tess.s),
+           dr = 0.5*(tess.r2 - tess.r1),
+           ws[2], ss[2], r1s[2];
+    int i, j, k, t = 0;
+
+    ws[0] = tess.w;
+    ws[1] = tess.w + dlon;
+    ss[0] = tess.s;
+    ss[1] = tess.s + dlat;
+    r1s[0] = tess.r1;
+    r1s[1] = tess.r1 + dr;
+    for(k = 0; k < 2; k++)
+    {
+        for(j = 0; j < 2; j++)
+        {
+            for(i = 0; i < 2; i++)
+            {
+                split[t].w = ws[i];
+                split[t].e = ws[i] + dlon;
+                split[t].s = ss[j];
+                split[t].n = ss[j] + dlat;
+                split[t].r1 = r1s[k];
+                split[t].r2 = r1s[k] + dr;
+                split[t].density = tess.density;
+                t++;
+            }
+        }
+    }
+}