--- trunk/OOPSE/libmdtools/f_verlet_constrained.F90	2003/03/24 15:26:05	389
+++ trunk/OOPSE/libmdtools/f_verlet_constrained.F90	2003/04/25 02:00:11	505
@@ -49,6 +49,7 @@ subroutine v_constrain_a(dt,natoms,mass,rx,ry,rz, &
   double precision pxab, pyab, pzab, pabsq, rabsq, diffsq
   double precision rxab, ryab, rzab, rpab, gab
   double precision dx, dy, dz, rma, rmb
+  double precision prSqr, rpabSqr;
   integer a, b, it, maxit
   parameter (rptol = 1.0d-6, tol = 1.0d-6 )
   parameter ( maxit = 100 )
@@ -58,7 +59,7 @@ subroutine v_constrain_a(dt,natoms,mass,rx,ry,rz, &
   double precision e_convert
   parameter ( e_convert = 4.184d-4 )
   
-
+ 
   DT2   = DT / 2.0d0
   DTSQ2 = DT * DT2
   
@@ -127,9 +128,12 @@ subroutine v_constrain_a(dt,natoms,mass,rx,ry,rz, &
 
               rpab = rxab * pxab + ryab * pyab + rzab * pzab
               
-              if( dabs(rpab) .lt. ( rabsq * rptol ) ) then
+              rpabSqr = rpab * rpab
+              prSqr = - diffsq
+
+              if( rpabSqr .lt. ( rabsq * prSqr )) then
                  write (*, '('' Constraint Failure '')' )
-                 write (*,*) a-1, b-1,rpab, rabsq * rptol
+                 write (*,*) a-1, b-1,rpabSqr, rabsq * prSqr
                  stop
               end if
               
@@ -194,7 +198,6 @@ subroutine v_constrain_a(dt,natoms,mass,rx,ry,rz, &
   enddo
   
   
-  
   RETURN
 end subroutine v_constrain_a