1 files changed, 67 insertions, 0 deletions
diff --git a/src/projections/putp3.cpp b/src/projections/putp3.cpp
new file mode 100644
index 00000000..98bb2ff0
--- /dev/null
+++ b/src/projections/putp3.cpp
@@ -0,0 +1,67 @@
+#define PJ_LIB__
+#include <errno.h>
+#include "projects.h"
+
+namespace { // anonymous namespace
+struct pj_opaque {
+    double  A;
+};
+} // anonymous namespace
+
+PROJ_HEAD(putp3, "Putnins P3") "\n\tPCyl, Sph";
+PROJ_HEAD(putp3p, "Putnins P3'") "\n\tPCyl, Sph";
+
+#define C       0.79788456
+#define RPISQ   0.1013211836
+
+
+static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
+    XY xy = {0.0,0.0};
+
+    xy.x = C * lp.lam * (1. - static_cast<struct pj_opaque*>(P->opaque)->A * lp.phi * lp.phi);
+    xy.y = C * lp.phi;
+
+    return xy;
+}
+
+
+static LP s_inverse (XY xy, PJ *P) {           /* Spheroidal, inverse */
+    LP lp = {0.0,0.0};
+
+    lp.phi = xy.y / C;
+    lp.lam = xy.x / (C * (1. - static_cast<struct pj_opaque*>(P->opaque)->A * lp.phi * lp.phi));
+
+    return lp;
+}
+
+
+PJ *PROJECTION(putp3) {
+    struct pj_opaque *Q = static_cast<struct pj_opaque*>(pj_calloc (1, sizeof (struct pj_opaque)));
+    if (nullptr==Q)
+        return pj_default_destructor (P, ENOMEM);
+    P->opaque = Q;
+
+    Q->A = 4. * RPISQ;
+
+    P->es = 0.;
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+
+    return P;
+}
+
+PJ *PROJECTION(putp3p) {
+    struct pj_opaque *Q = static_cast<struct pj_opaque*>(pj_calloc (1, sizeof (struct pj_opaque)));
+    if (nullptr==Q)
+        return pj_default_destructor (P, ENOMEM);
+    P->opaque = Q;
+
+    Q->A = 2. * RPISQ;
+
+    P->es = 0.;
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+
+    return P;
+}
+