added Shewchuk's robust geometrical predicates (since they can be duplicated in
Tetgen/triangle I've put them in the gmsh namespace)

Mesh/2D_DivAndConq.cpp

-// $Id: 2D_DivAndConq.cpp,v 1.22 2006-09-11 15:23:54 remacle Exp $
+// $Id: 2D_DivAndConq.cpp,v 1.23 2006-09-11 17:58:19 geuzaine Exp $
 //
 // Copyright (C) 1997-2006 C. Geuzaine, J.-F. Remacle
 //
@@ -183,53 +183,22 @@ Segment UpperCommonTangent(DT vl, DT vr)
 
 /* return 1 if the point k is NOT in the circumcircle of
    triangle hij */
-#ifndef HAVE_TETGEN
 int Qtest(PointNumero h, PointNumero i, PointNumero j, PointNumero k)
 {
-  double xc, yc, rcarre, distca;
-
-  if((h == i) && (h == j) && (h == k)) {
-    Msg(GERROR, "3 identical points in Qtest");
-    return (0); /* returning 1 will cause looping for ever */
-  }
-  if(CircumCircle((double)pPointArray[h].where.h,
-                  (double)pPointArray[h].where.v,
-                  (double)pPointArray[i].where.h,
-                  (double)pPointArray[i].where.v,
-                  (double)pPointArray[j].where.h,
-                  (double)pPointArray[j].where.v, &xc, &yc)) {
-    rcarre = square(xc - (double)pPointArray[i].where.h) +
-      square(yc - (double)pPointArray[i].where.v);
-
-    distca = square(xc - (double)pPointArray[k].where.h) +
-      square(yc - (double)pPointArray[k].where.v);
-
-    return (distca > rcarre);
-  }
-  else
-    return (0); /* point not in circle, because no circle !     */
-}
-#else 
-#include "tetgen.h"
-int Qtest(PointNumero h, PointNumero i, PointNumero j, PointNumero k)
-{
-  exactinit() ;
   if((h == i) && (h == j) && (h == k)) {
     Msg(GERROR, "3 identical points in Qtest");
     return (0); /* returning 1 will cause looping for ever */
   }
   
-  REAL pa[2] = {(REAL)pPointArray[h].where.h,(REAL)pPointArray[h].where.v};
-  REAL pb[2] = {(REAL)pPointArray[i].where.h,(REAL)pPointArray[i].where.v};
-  REAL pc[2] = {(REAL)pPointArray[j].where.h,(REAL)pPointArray[j].where.v};
-  REAL pd[2] = {(REAL)pPointArray[k].where.h,(REAL)pPointArray[k].where.v};
+  double pa[2] = {(double)pPointArray[h].where.h, (double)pPointArray[h].where.v};
+  double pb[2] = {(double)pPointArray[i].where.h, (double)pPointArray[i].where.v};
+  double pc[2] = {(double)pPointArray[j].where.h, (double)pPointArray[j].where.v};
+  double pd[2] = {(double)pPointArray[k].where.h, (double)pPointArray[k].where.v};
   
-  REAL result = incircle ( pa, pb, pc, pd ) * orient2d (pa,pb,pc);
-  //  Msg(INFO, "Qtest %12.5E",result);
+  double result = gmsh::incircle(pa, pb, pc, pd) * gmsh::orient2d(pa, pb, pc);
   
-  return (result < 0)?1:0;
+  return (result < 0) ? 1 : 0;
 }
-#endif
 
 
 int merge(DT vl, DT vr)

Numeric/Makefile

-# $Id: Makefile,v 1.28 2006-08-04 14:28:03 geuzaine Exp $
+# $Id: Makefile,v 1.29 2006-09-11 17:58:19 geuzaine Exp $
 #
 # Copyright (C) 1997-2006 C. Geuzaine, J.-F. Remacle
 #
@@ -27,6 +27,7 @@ CFLAGS  = ${OPTIM} ${FLAGS} ${INCLUDE}
 
 SRC = Numeric.cpp\
       EigSolve.cpp\
+      predicates.cpp\
       gsl_newt.cpp\
       gsl_brent.cpp
 

Numeric/Numeric.cpp

-// $Id: Numeric.cpp,v 1.27 2006-08-16 05:25:22 geuzaine Exp $
+// $Id: Numeric.cpp,v 1.28 2006-09-11 17:58:19 geuzaine Exp $
 //
 // Copyright (C) 1997-2006 C. Geuzaine, J.-F. Remacle
 //
@@ -58,6 +58,11 @@ int check_gsl()
   }
   // set new error handler
   gsl_set_error_handler(&new_handler);
+
+  
+  // initilize robust geometric predicates
+  gmsh::exactinit() ;
+
   return 1;
 }
 
@@ -65,6 +70,10 @@ int check_gsl()
 
 int check_gsl()
 {
+
+  // initilize robust geometric predicates
+  gmsh::exactinit() ;
+
   return 1;
 }
 

Numeric/Numeric.h

@@ -97,4 +97,13 @@ void mnbrak(double *ax, double *bx, double *cx, double *fa, double *fb,
 void newt(double x[], int n, int *check,
 	  void (*vecfunc)(int, double [], double []));
 
+/* Robust geometrical predicates */
+namespace gmsh{
+double exactinit();
+double incircle(double *pa, double *pb, double *pc, double *pd);
+double insphere(double *pa, double *pb, double *pc, double *pd, double *pe);
+double orient2d(double *pa, double *pb, double *pc);
+double orient3d(double *pa, double *pb, double *pc, double *pd);
+}
+
 #endif