Correction of inverse function in gstmerc : point of projected origin was descaled.

Comments added in testIGNF header (reminder) : null grid is mandatory, otherwise tests failed.
Adding logs to ChangeLog.

git-svn-id: http://svn.osgeo.org/metacrs/proj/trunk@1540 4e78687f-474d-0410-85f9-8d5e500ac6b2

3 files changed, 21 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index c9cf86a6..f781aeec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2009-03-08	IGNF <didier.richard@ign.fr>
+
+	* src/PJ_gstmerc.c: Correction of a bug in inv() function :
+	the projected origin coordinates where descaled.
+
+	* nad/testIGNF: Add a comment on the mandatory existance of the world grid
+	in order to make the test.
+
+	* ChangeLog: this comments
+
 2009-01-26  Frank Warmerdam  <warmerdam@pobox.com>
 
 	* src/*.c: Remove SCCSID and lint stuff from all source files.
diff --git a/nad/testIGNF b/nad/testIGNF
index 1e451871..ec782eb6 100755
--- a/nad/testIGNF
+++ b/nad/testIGNF
@@ -5,6 +5,9 @@
 # Real points locations are found in proj_outIGNF.dist-real
 # while distribution results are found in proj_outIGNF.dist
 #
+# 2009-03-08 :  the null grid (nad2bin < null.lla null) MUST
+#               be around otherwise the LAMBE to LAMB93
+#               transformations will be wrong and vice-versa
 EXE=$1
 
 usage()
diff --git a/src/PJ_gstmerc.c b/src/PJ_gstmerc.c
index bd01f8cf..23b86ee8 100644
--- a/src/PJ_gstmerc.c
+++ b/src/PJ_gstmerc.c
@@ -19,26 +19,30 @@ FORWARD(s_forward); /* spheroid */
     Ls1= log(pj_tsfn(-1.0*asin(sinLs1),0.0,0.0));
     xy.x= (P->XS + P->n2*Ls1)*P->ra;
     xy.y= (P->YS + P->n2*atan(sinh(Ls)/cos(L)))*P->ra;
+    /*fprintf(stderr,"fwd:\nL      =%16.13f\nLs     =%16.13f\nLs1    =%16.13f\nLP(%16.13f,%16.13f)=XY(%16.4f,%16.4f)\n",L,Ls,Ls1,lp.lam+P->lam0,lp.phi,(xy.x*P->a + P->x0)*P->to_meter,(xy.y*P->a + P->y0)*P->to_meter);*/
 	return (xy);
 }
 INVERSE(s_inverse); /* spheroid */
 	double L, LC, sinC;
-	L= atan(sinh((xy.x - P->XS)*P->a/P->n2)/cos((xy.y - P->YS)*P->a/P->n2));
-    sinC= sin((xy.y - P->YS)*P->a/P->n2)/cosh((xy.x - P->XS)*P->a/P->n2);
+	L= atan(sinh((xy.x*P->a - P->XS)/P->n2)/cos((xy.y*P->a - P->YS)/P->n2));
+    sinC= sin((xy.y*P->a - P->YS)/P->n2)/cosh((xy.x*P->a - P->XS)/P->n2);
     LC= log(pj_tsfn(-1.0*asin(sinC),0.0,0.0));
     lp.lam= L/P->n1;
     lp.phi= -1.0*pj_phi2(exp((LC-P->c)/P->n1),P->e);
+    /*fprintf(stderr,"inv:\nL      =%16.13f\nsinC   =%16.13f\nLC     =%16.13f\nXY(%16.4f,%16.4f)=LP(%16.13f,%16.13f)\n",L,sinC,LC,((xy.x/P->ra)+P->x0)/P->to_meter,((xy.y/P->ra)+P->y0)/P->to_meter,lp.lam+P->lam0,lp.phi);*/
 	return (lp);
 }
 FREEUP; if (P) pj_dalloc(P); }
 ENTRY0(gstmerc)
+    P->lamc= P->lam0;
     P->n1= sqrt(1.0+P->es*pow(cos(P->phi0),4.0)/(1.0-P->es));
     P->phic= asin(sin(P->phi0)/P->n1);
     P->c=       log(pj_tsfn(-1.0*P->phic,0.0,0.0))
          -P->n1*log(pj_tsfn(-1.0*P->phi0,-1.0*sin(P->phi0),P->e));
     P->n2= P->k0*P->a*sqrt(1.0-P->es)/(1.0-P->es*sin(P->phi0)*sin(P->phi0));
-    P->XS= 0;
-    P->YS= -1.0*P->n2*P->phic;
+    P->XS= 0;/* -P->x0 */
+    P->YS= -1.0*P->n2*P->phic;/* -P->y0 */
 	P->inv= s_inverse;
 	P->fwd= s_forward;
+    /*fprintf(stderr,"a  (m) =%16.4f\ne      =%16.13f\nl0(rad)=%16.13f\np0(rad)=%16.13f\nk0     =%16.4f\nX0  (m)=%16.4f\nY0  (m)=%16.4f\n\nlC(rad)=%16.13f\npC(rad)=%16.13f\nc      =%16.13f\nn1     =%16.13f\nn2 (m) =%16.4f\nXS (m) =%16.4f\nYS (m) =%16.4f\n", P->a, P->e, P->lam0, P->phi0, P->k0, P->x0, P->y0, P->lamc, P->phic, P->c, P->n1, P->n2, P->XS +P->x0, P->YS + P->y0);*/
 ENDENTRY(P)