From b0fb037ea22e2e9452feda502455ac6110c3e1e3 Mon Sep 17 00:00:00 2001
From: Charles Karney <ckarney@karney.com>
Date: Sat, 24 Oct 2015 11:36:25 -0400
Subject: Switch utm to use etmerc to address issue #316.

Add a test to check this.  Output of an existing test changed in 7th
decimal place.
---
 src/PJ_tmerc.c    | 22 ----------------------
 src/proj_etmerc.c | 33 +++++++++++++++++++++++++++++++--
 src/projects.h    |  2 +-
 3 files changed, 32 insertions(+), 25 deletions(-)

(limited to 'src')

diff --git a/src/PJ_tmerc.c b/src/PJ_tmerc.c
index 3b1e0fb5..70e8e72f 100644
--- a/src/PJ_tmerc.c
+++ b/src/PJ_tmerc.c
@@ -5,8 +5,6 @@
 #define PJ_LIB__
 #include	<projects.h>
 PROJ_HEAD(tmerc, "Transverse Mercator") "\n\tCyl, Sph&Ell";
-PROJ_HEAD(utm, "Universal Transverse Mercator (UTM)")
-	"\n\tCyl, Sph\n\tzone= south";
 #define EPS10	1.e-10
 #define aks0	P->esp
 #define aks5	P->ml0
@@ -153,23 +151,3 @@ setup(PJ *P) { /* general initialization */
 }
 ENTRY1(tmerc, en)
 ENDENTRY(setup(P))
-ENTRY1(utm, en)
-	int zone;
-
-	if (!P->es) E_ERROR(-34);
-	P->y0 = pj_param(P->ctx, P->params, "bsouth").i ? 10000000. : 0.;
-	P->x0 = 500000.;
-	if (pj_param(P->ctx, P->params, "tzone").i) /* zone input ? */
-		if ((zone = pj_param(P->ctx, P->params, "izone").i) > 0 && zone <= 60)
-			--zone;
-		else
-			E_ERROR(-35)
-	else /* nearest central meridian input */
-		if ((zone = floor((adjlon(P->lam0) + PI) * 30. / PI)) < 0)
-			zone = 0;
-		else if (zone >= 60)
-			zone = 59;
-	P->lam0 = (zone + .5) * PI / 30. - PI;
-	P->k0 = 0.9996;
-	P->phi0 = 0.;
-ENDENTRY(setup(P))
diff --git a/src/proj_etmerc.c b/src/proj_etmerc.c
index 1097eb3c..a5351f5d 100644
--- a/src/proj_etmerc.c
+++ b/src/proj_etmerc.c
@@ -52,6 +52,8 @@
 
 PROJ_HEAD(etmerc, "Extended Transverse Mercator")
     "\n\tCyl, Sph\n\tlat_ts=(0)\nlat_0=(0)";
+PROJ_HEAD(utm, "Universal Transverse Mercator (UTM)")
+	"\n\tCyl, Sph\n\tzone= south";
 
 #define PROJ_ETMERC_ORDER 6
 
@@ -211,7 +213,8 @@ INVERSE(e_inverse); /* ellipsoid */
 
 FREEUP; if (P) free(P); }
 
-ENTRY0(etmerc)
+	static PJ *
+setup(PJ *P) { /* general initialization */
     double f, n, np, Z;
 
     if (P->es <= 0) E_ERROR(-34);
@@ -286,4 +289,30 @@ ENTRY0(etmerc)
     P->Zb  = - P->Qn*(Z + clens(P->gtu, PROJ_ETMERC_ORDER, 2*Z));
     P->inv = e_inverse;
     P->fwd = e_forward;
-ENDENTRY(P)
+	return P;
+}
+
+ENTRY0(etmerc)
+ENDENTRY(setup(P))
+
+/* utm uses etmerc for the underlying projection */
+ENTRY0(utm)
+	int zone;
+
+	if (!P->es) E_ERROR(-34);
+	P->y0 = pj_param(P->ctx, P->params, "bsouth").i ? 10000000. : 0.;
+	P->x0 = 500000.;
+	if (pj_param(P->ctx, P->params, "tzone").i) /* zone input ? */
+		if ((zone = pj_param(P->ctx, P->params, "izone").i) > 0 && zone <= 60)
+			--zone;
+		else
+			E_ERROR(-35)
+	else /* nearest central meridian input */
+		if ((zone = floor((adjlon(P->lam0) + PI) * 30. / PI)) < 0)
+			zone = 0;
+		else if (zone >= 60)
+			zone = 59;
+	P->lam0 = (zone + .5) * PI / 30. - PI;
+	P->k0 = 0.9996;
+	P->phi0 = 0.;
+ENDENTRY(setup(P))
diff --git a/src/projects.h b/src/projects.h
index fe6a44c6..43287849 100644
--- a/src/projects.h
+++ b/src/projects.h
@@ -316,7 +316,7 @@ extern struct PJ_PRIME_MERIDIANS pj_prime_meridians[];
 #endif
 
 #ifdef PJ_LIB__
-    /* repeatative projection code */
+    /* repetitive projection code */
 #define PROJ_HEAD(id, name) static const char des_##id [] = name
 #define ENTRYA(name) \
         C_NAMESPACE_VAR const char * const pj_s_##name = des_##name; \
-- 
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