1 files changed, 41 insertions, 0 deletions
diff --git a/src/projections/PJ_eck1.cpp b/src/projections/PJ_eck1.cpp
new file mode 100644
index 00000000..88a7430c
--- /dev/null
+++ b/src/projections/PJ_eck1.cpp
@@ -0,0 +1,41 @@
+#define PJ_LIB__
+#include <math.h>
+
+#include "projects.h"
+
+PROJ_HEAD(eck1, "Eckert I") "\n\tPCyl, Sph";
+#define FC  0.92131773192356127802
+#define RP  0.31830988618379067154
+
+
+static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
+    XY xy = {0.0,0.0};
+    (void) P;
+
+    xy.x = FC * lp.lam * (1. - RP * fabs(lp.phi));
+    xy.y = FC * lp.phi;
+
+    return xy;
+}
+
+
+static LP s_inverse (XY xy, PJ *P) {           /* Spheroidal, inverse */
+    LP lp = {0.0,0.0};
+    (void) P;
+
+    lp.phi = xy.y / FC;
+    lp.lam = xy.x / (FC * (1. - RP * fabs(lp.phi)));
+
+    return (lp);
+}
+
+
+
+PJ *PROJECTION(eck1) {
+    P->es = 0.0;
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+
+    return P
+;
+}