source: osm/applications/editors/josm/plugins/proj4j/patches/01proj4j-transverse-mercator-fix.patch@ 26606

src/org/osgeo/proj4j/proj/TransverseMercatorProjection.java

@@ -16 +16 @@
 
 /*
  * This file was semi-automatically converted from the public-domain USGS PROJ source.
+ *
+ * Bernhard Jenny, February 2 2010: Corrected code for spherical case in
+ * projectInverse, added isConformal.
+ * 27 September 2010: added missing tests to forward spherical, removed
+ * initialization code in constructor.
  */
 package org.osgeo.proj4j.proj;
 
@@ -154 +159 @@
 
         public ProjCoordinate projectInverse(double x, double y, ProjCoordinate out) {
                 if (spherical) {
-                        double h = Math.exp(x / scaleFactor);
-                        double g = .5 * (h - 1. / h);
-                        h = Math.cos(projectionLatitude + y / scaleFactor);
-                        out.y = ProjectionMath.asin(Math.sqrt((1. - h*h) / (1. + g*g)));
-                        if (y < 0)
-                                out.y = -out.y;
-                        out.x = Math.atan2(g, h);
+                        /*
+                        Original code
+                        x = Math.exp(x / scaleFactor);
+                        y = .5 * (x - 1. / x);
+                        x = Math.cos(projectionLatitude + y / scaleFactor);
+                        out.y = MapMath.asin(Math.sqrt((1. - x * x) / (1. + y * y)));
+                        if (y < 0) {
+                        out.y = -out.y;
+                        }
+                        out.x = Math.atan2(y, x);
+                         */
+
+                        // new code by Bernhard Jenny, February 2 2010
+                        double D = y / scaleFactor + projectionLatitude;
+                        double xp = x / scaleFactor;
+
+                        out.y = Math.asin(Math.sin(D) / Math.cosh(xp));
+                        out.x = Math.atan2(Math.sinh(xp), Math.cos(D));
                 } else {
                         double n, con, cosphi, d, ds, sinphi, t;
 
@@ -196 +212 @@
         public boolean hasInverse() {
                 return true;
         }
+        
+        public boolean isConformal() {
+                return true;
+        }
 
         public String toString() {
     if (utmZone >= 0)