--- trunk/OOPSE/libmdtools/RigidBody.cpp	2004/04/15 16:18:26	1113
+++ trunk/OOPSE/libmdtools/RigidBody.cpp	2004/04/19 03:52:27	1118
@@ -6,6 +6,8 @@ RigidBody::RigidBody() : StuntDouble() {
 
 RigidBody::RigidBody() : StuntDouble() {
   objType = OT_RIGIDBODY;
+  is_linear = false;
+  linear_axis =  -1;
 }
 
 RigidBody::~RigidBody() {
\ No newline at end of file
@@ -261,7 +263,7 @@ void RigidBody::calcRefCoords( ) {
 
 void RigidBody::calcRefCoords( ) {
 
-  int i,j,k, it;
+  int i,j,k, it, n_linear_coords;
   double mtmp;
   vec3 apos;
   double refCOM[3];
\ No newline at end of file
@@ -328,11 +330,33 @@ void RigidBody::calcRefCoords( ) {
   
   // zero out I and then fill the diagonals with the moments of inertia:
 
+  n_linear_coords = 0;
+
   for (i = 0; i < 3; i++) {
     for (j = 0; j < 3; j++) {
       I[i][j] = 0.0;  
     }
     I[i][i] = evals[i];
+
+    if (fabs(evals[i]) < momIntTol) {
+      is_linear = true;
+      n_linear_coords++;
+      linear_axis = i;
+    }
+  }
+
+  if (n_linear_coords > 1) {
+          sprintf( painCave.errMsg,
+               "RigidBody error.\n"
+               "\tOOPSE found more than one axis in this rigid body with a vanishing \n"
+               "\tmoment of inertia.  This can happen in one of three ways:\n"
+               "\t 1) Only one atom was specified, or \n"
+               "\t 2) All atoms were specified at the same location, or\n"
+               "\t 3) The programmers did something stupid.\n"
+               "\tIt is silly to use a rigid body to describe this situation.  Be smarter.\n"
+               );
+      painCave.isFatal = 1;
+      simError();
   }
   
   // renormalize column vectors:
\ No newline at end of file
@@ -601,3 +625,11 @@ void RigidBody::findCOM() {
   }
 
 }
+
+void RigidBody::accept(BaseVisitor* v){
+  vector<Atom*>::iterator atomIter;
+  v->visit(this);
+
+  for(atomIter = myAtoms.begin(); atomIter != myAtoms.end(); ++atomIter)
+    (*atomIter)->accept(v);
+}
\ No newline at end of file