1 files changed, 84 insertions, 0 deletions
diff --git a/src/projections/comill.cpp b/src/projections/comill.cpp
new file mode 100644
index 00000000..b6e0192e
--- /dev/null
+++ b/src/projections/comill.cpp
@@ -0,0 +1,84 @@
+/*
+The Compact Miller projection was designed by Tom Patterson, US National
+Park Service, in 2014. The polynomial equation was developed by Bojan
+Savric and Bernhard Jenny, College of Earth, Ocean, and Atmospheric
+Sciences, Oregon State University.
+Port to PROJ.4 by Bojan Savric, 4 April 2016
+*/
+
+#define PJ_LIB__
+
+#include <math.h>
+
+#include "projects.h"
+
+PROJ_HEAD(comill, "Compact Miller") "\n\tCyl, Sph";
+
+#define K1 0.9902
+#define K2 0.1604
+#define K3 -0.03054
+#define C1 K1
+#define C2 (3 * K2)
+#define C3 (5 * K3)
+#define EPS 1e-11
+#define MAX_Y (0.6000207669862655 * M_PI)
+/* Not sure at all of the appropriate number for MAX_ITER... */
+#define MAX_ITER 100
+
+static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
+    XY xy = {0.0,0.0};
+    double lat_sq;
+
+    (void) P;   /* silence unused parameter warnings */
+
+    lat_sq = lp.phi * lp.phi;
+    xy.x = lp.lam;
+    xy.y = lp.phi * (K1 + lat_sq * (K2 + K3 * lat_sq));
+    return xy;
+}
+
+
+static LP s_inverse (XY xy, PJ *P) {           /* Spheroidal, inverse */
+    LP lp = {0.0,0.0};
+    double yc, tol, y2, f, fder;
+    int i;
+
+    (void) P;   /* silence unused parameter warnings */
+
+    /* make sure y is inside valid range */
+    if (xy.y > MAX_Y) {
+        xy.y = MAX_Y;
+    } else if (xy.y < -MAX_Y) {
+        xy.y = -MAX_Y;
+    }
+
+    /* latitude */
+    yc = xy.y;
+    for (i = MAX_ITER; i ; --i) { /* Newton-Raphson */
+        y2 = yc * yc;
+        f = (yc * (K1 + y2 * (K2 + K3 * y2))) - xy.y;
+        fder = C1 + y2 * (C2 + C3 * y2);
+        yc -= tol = f / fder;
+        if (fabs(tol) < EPS) {
+            break;
+        }
+    }
+    if( i == 0 )
+        pj_ctx_set_errno( P->ctx, PJD_ERR_NON_CONVERGENT );
+    lp.phi = yc;
+
+    /* longitude */
+    lp.lam = xy.x;
+
+    return lp;
+}
+
+
+PJ *PROJECTION(comill) {
+    P->es = 0;
+
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+
+    return P;
+}