From 3038315ab1cde75268a474a3170215d887f0c583 Mon Sep 17 00:00:00 2001
From: Micah Cochran <micahcochran@users.noreply.github.com>
Date: Sun, 27 Mar 2016 10:54:51 -0500
Subject: Add Patterson Cylindrical projection.  Add tests for projection.

---
 src/Makefile.am    |  2 +-
 src/PJ_patterson.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/lib_proj.cmake |  1 +
 src/pj_list.h      |  1 +
 4 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 src/PJ_patterson.c

(limited to 'src')

diff --git a/src/Makefile.am b/src/Makefile.am
index 871f8478..6fd97475 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -52,7 +52,7 @@ libproj_la_SOURCES = \
 	PJ_eck5.c PJ_fahey.c PJ_fouc_s.c PJ_gins8.c PJ_gstmerc.c \
 	PJ_gn_sinu.c PJ_goode.c PJ_igh.c PJ_hatano.c PJ_loxim.c \
 	PJ_mbt_fps.c PJ_mbtfpp.c PJ_mbtfpq.c PJ_moll.c \
-	PJ_nell.c PJ_nell_h.c PJ_putp2.c PJ_putp3.c \
+	PJ_nell.c PJ_nell_h.c PJ_patterson.c PJ_putp2.c PJ_putp3.c \
 	PJ_putp4p.c PJ_putp5.c PJ_putp6.c PJ_qsc.c PJ_robin.c \
 	PJ_sch.c PJ_sts.c PJ_urm5.c PJ_urmfps.c PJ_wag2.c \
 	PJ_wag3.c PJ_wink1.c PJ_wink2.c pj_latlong.c pj_geocent.c \
diff --git a/src/PJ_patterson.c b/src/PJ_patterson.c
new file mode 100644
index 00000000..0483bf6e
--- /dev/null
+++ b/src/PJ_patterson.c
@@ -0,0 +1,64 @@
+/*
+ * The Patterson projection was designed by Tom Patterson, US National
+ * Park Service, in 2014, using Flex Projector. The polynomial equations for the
+ * projection were developed by Bojan Savric, Oregon State University, in
+ * collaboration with Tom Patterson and Bernhard Jenny, Oregon State University.
+ *
+ * Java reference algorithm implemented by Bojan Savric in JMapProjLib
+ * project (file PattersonProjection.java)
+ *
+ * Port to Proj.4 by Micah Cochran, 26 March 2016
+ */
+
+#define PJ_LIB__
+# include	<projects.h>
+PROJ_HEAD(patterson, "Patterson Cylindrical") "\n\tCyl.";
+#define K1 1.0148
+#define K2 0.23185
+#define K3 -0.14499
+#define K4 0.02406
+#define C1 K1
+#define C2 (5.0 * K2)
+#define C3 (7.0 * K3)
+#define C4 (9.0 * K4)
+#define EPS11 1.0e-11
+#define MAX_Y 1.790857183
+
+FORWARD(s_forward); /* spheroid */
+    double phi2;
+	(void) P;
+    phi2 = lp.phi * lp.phi;
+	xy.x = lp.lam;
+    xy.y = lp.phi * (K1 + phi2 * phi2 * (K2 + phi2 * (K3 + K4 * phi2)));
+	return (xy);
+}
+INVERSE(s_inverse); /* spheroid */
+    double yc, tol, y2, f, fder;
+	(void) P;
+    yc = xy.y;
+    
+    /* 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;
+    }
+    
+    for (;;) { /* Newton-Raphson */
+		y2 = yc * yc;
+		f = (yc * (K1 + y2 * y2 * (K2 + y2 * (K3 + K4 * y2)))) - xy.y;
+		fder = C1 + y2 * y2 * (C2 + y2 * (C3 + C4 * y2));
+		yc -= tol = f / fder;
+		if (fabs(tol) < EPS11) {
+			break;
+		}
+	}
+    lp.phi = yc;
+    
+    /* longitude */
+	lp.lam = xy.x;
+	
+	return (lp);
+}
+FREEUP; if (P) pj_dalloc(P); }
+ENTRY0(patterson) P->es = 0.; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)
diff --git a/src/lib_proj.cmake b/src/lib_proj.cmake
index 85207e87..a8797a74 100644
--- a/src/lib_proj.cmake
+++ b/src/lib_proj.cmake
@@ -107,6 +107,7 @@ SET(SRC_LIBPROJ_PJ
         PJ_oea.c
         PJ_omerc.c
         PJ_ortho.c
+        PJ_patterson.c
         PJ_poly.c
         PJ_putp2.c
         PJ_putp3.c
diff --git a/src/pj_list.h b/src/pj_list.h
index 338eb2dd..47362d87 100644
--- a/src/pj_list.h
+++ b/src/pj_list.h
@@ -97,6 +97,7 @@ PROJ_HEAD(omerc, "Oblique Mercator")
 PROJ_HEAD(ortel, "Ortelius Oval")
 PROJ_HEAD(ortho, "Orthographic")
 PROJ_HEAD(pconic, "Perspective Conic")
+PROJ_HEAD(patterson, "Patterson Cylindrical")
 PROJ_HEAD(poly, "Polyconic (American)")
 PROJ_HEAD(putp1, "Putnins P1")
 PROJ_HEAD(putp2, "Putnins P2")
-- 
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