1 files changed, 36 insertions, 0 deletions
diff --git a/src/projections/tcea.cpp b/src/projections/tcea.cpp
new file mode 100644
index 00000000..d30f3df0
--- /dev/null
+++ b/src/projections/tcea.cpp
@@ -0,0 +1,36 @@
+#define PJ_LIB__
+
+#include <math.h>
+
+#include "projects.h"
+
+PROJ_HEAD(tcea, "Transverse Cylindrical Equal Area") "\n\tCyl, Sph";
+
+
+static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
+    XY xy = {0.0,0.0};
+    xy.x = cos (lp.phi) * sin (lp.lam) / P->k0;
+    xy.y = P->k0 * (atan2 (tan (lp.phi), cos (lp.lam)) - P->phi0);
+    return xy;
+}
+
+
+static LP s_inverse (XY xy, PJ *P) {           /* Spheroidal, inverse */
+    LP lp = {0.0, 0.0};
+    double t;
+
+    xy.y = xy.y / P->k0 + P->phi0;
+    xy.x *= P->k0;
+    t = sqrt (1. - xy.x * xy.x);
+    lp.phi = asin (t * sin (xy.y));
+    lp.lam = atan2 (xy.x, t * cos (xy.y));
+    return lp;
+}
+
+
+PJ *PROJECTION(tcea) {
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+    P->es = 0.;
+    return P;
+}