added new projection function for Navionics Mercator

src/Makefile.am

@@ -39,7 +39,7 @@ libproj_la_SOURCES = \
 	PJ_imw_p.c PJ_krovak.c PJ_lcc.c PJ_poly.c \
 	PJ_rpoly.c PJ_sconics.c proj_rouss.c \
 	PJ_cass.c PJ_cc.c PJ_cea.c PJ_eqc.c \
-	PJ_gall.c PJ_labrd.c PJ_lsat.c PJ_misrsom.c PJ_merc.c \
+	PJ_gall.c PJ_labrd.c PJ_lsat.c PJ_misrsom.c PJ_merc.c PJ_nav_merc.c \
 	PJ_mill.c PJ_ocea.c PJ_omerc.c PJ_somerc.c \
 	PJ_tcc.c PJ_tcea.c PJ_tmerc.c \
 	PJ_airy.c PJ_aitoff.c PJ_august.c PJ_bacon.c \

src/PJ_nav_merc.c

@@ -0,0 +1,132 @@
+/*
+ ***** Navionics Mercator ****************
+ * 
+ * (co)author pasquini.matteo@gmail.com, mpasquini@navionics.com
+ * 
+ * datum(barely speaking): 
+ * based on Hayford 1909  ellipsoid but geocentered.
+ * 
+ * attributes:
+ * 	- geocentered
+ * 	- a = 6378388
+ * 	- b = 6356912
+ * 	- (a/b)/a = 1/297.0
+ * 	- eccentricity = 0.081991889977 
+ * 	- KC = 1.00676429271698
+ * 
+ * orignal functions are in decimal degrees(instead radians)
+ * this implementation is(should be) the most precise in radians, 
+ * the first outside proprietary Navionics S.p.A. SDK
+ * 
+ * note the KC is a CONST value that substitute the P->e
+ * it have some similarity with PJ_merc and PJ_tsfn
+ * , all maths help are wellcome ...
+ * 
+ * This few lines represent a "small docs" 
+ * complete documentation is in .docx format, to not pollute this beautiful project 
+ * i prefer that you bother me throught email request.
+ * 
+ * this is my first piece of C in the real world.
+ *  
+ */
+
+
+
+#define PJ_LIB__
+#include <projects.h>
+
+PROJ_HEAD(nav_merc, "Navionics Mercator") "\n\tEll\n\tlat_ts=";
+
+#define EPS10 1.e-10
+#define KC 1.00676429271698
+
+
+static XY e_forward (LP lp, PJ *P) {          /* Ellipsoidal, forward */
+    XY xy = {0.0,0.0};
+    if (fabs(fabs(lp.phi) - M_HALFPI) <= EPS10)
+        F_ERROR; 
+
+    xy.y =  log(tan( .5 * atan (tan(lp.phi)/KC) + M_FORTPI) )  ; 
+    xy.x = P->k0 * lp.lam;
+    return (xy);
+}
+
+static LP e_inverse (XY xy, PJ *P) {          /* Ellipsoidal, inverse */
+    LP lp = {0.0,0.0};
+    if ((lp.phi = pj_phi2(P->ctx, exp(- xy.y / P->k0), P->e)) == HUGE_VAL)
+        I_ERROR;
+
+    lp.phi = atan2((tan((atan(exp(xy.y)) * 2.) - M_HALFPI) * KC), 1);
+    lp.lam = xy.x / P->k0;
+    return lp;
+}
+
+static void freeup(PJ *P) {                             /* Destructor */
+    pj_dealloc(P);
+}
+
+
+PJ *PROJECTION(nav_merc) {
+    double phits=0.0;
+    int is_phits;
+
+    if( (is_phits = pj_param(P->ctx, P->params, "tlat_ts").i) ) {
+        phits = fabs(pj_param(P->ctx, P->params, "rlat_ts").f);
+        if (phits >= M_HALFPI) E_ERROR(-24);
+    }
+
+    if (P->es) { /* ellipsoid */
+        if (is_phits)
+            P->k0 = pj_msfn(sin(phits), cos(phits), P->es);
+        P->inv = e_inverse;
+        P->fwd = e_forward;
+    }
+
+    return P;
+}
+
+
+#ifdef PJ_OMIT_SELFTEST
+int pj_nav_merc_selftest (void) {return 0;}
+#else
+
+int pj_nav_merc_selftest (void) {
+    double tolerance_lp = 1e-10;
+    double tolerance_xy = 1e-7;
+
+    char e_args[] = {" -w6 +proj=nav_merc +a=6378388.0 +rf=297"};
+
+    LP fwd_in[] = {
+        { 950594.539, 5968306.230 },
+        { 1178796.03, 5276463.78 },
+        { 18671158.340, -5945578.371 },
+        { 20038296.88, -18765191.35 }
+    };
+
+    XY e_fwd_expect[] = {
+        { 8.5390000000, 47.3515666667 },
+        { 10.5888881683, 42.9574966432 },
+        { 167.7192687988, -47.2126350403 },
+        { 179.9998888889, -84.0 },
+    };
+
+    XY inv_in[] = {
+        { 8.5390000000, 47.3515666667 },
+        { 10.5888881683, 42.9574966432 },
+        { 167.7192687988, -47.2126350403 },
+        { 180.0, -84.0 }
+    };
+
+    LP e_inv_expect[] = {
+        { 950594.539, 5968306.230 },
+        { 1178796.03, 5276463.78 },
+        { 18671158.340, -5945578.371 },
+        { 20038296.883, -18765191.347 },
+    };
+
+
+    return pj_generic_selftest (e_args, 0, tolerance_xy, tolerance_lp, 4, 4, fwd_in, 0, e_fwd_expect, inv_in, 0, e_inv_expect );
+}
+
+
+#endif

src/lib_proj.cmake

@@ -99,6 +99,7 @@ SET(SRC_LIBPROJ_PJ
         PJ_moll.c
         PJ_natearth.c
         PJ_natearth2.c
+	PJ_nav_merc.c
         PJ_nell.c
         PJ_nell_h.c
         PJ_nocol.c

src/pj_list.h

@@ -78,6 +78,7 @@ PROJ_HEAD(mbtfpp, "McBride-Thomas Flat-Polar Parabolic")
 PROJ_HEAD(mbtfpq, "McBryde-Thomas Flat-Polar Quartic")
 PROJ_HEAD(mbtfps, "McBryde-Thomas Flat-Polar Sinusoidal")
 PROJ_HEAD(merc, "Mercator")
+PROJ_HEAD(nav_merc, "Navionics Mercator")
 PROJ_HEAD(mil_os, "Miller Oblated Stereographic")
 PROJ_HEAD(mill, "Miller Cylindrical")
 PROJ_HEAD(misrsom, "Space oblique for MISR")