ADDED   mttroot/mtt/lib/comp/simple/EBTF_cause.m
Index: mttroot/mtt/lib/comp/simple/EBTF_cause.m
==================================================================
--- /dev/null
+++ mttroot/mtt/lib/comp/simple/EBTF_cause.m
@@ -0,0 +1,67 @@
+function [bonds,status] = EBTF_cause(bonds);
+% EBTF_cause - causality for a EBTF component
+% 
+%     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+%     %%%%% Model Transformation Tools %%%%%
+%     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% 
+% Matlab function  EBTF_cause
+% [bonds,status] = EBTF_cause(bonds)
+
+%SUMMARY EBTF: transformer component - bicausal on effort
+%DESCRIPTION Energy conserving two-port
+%DESCRIPTION e_1 f_1 = e_2 f_2 and e_1 and e_2 are both imposed.
+
+
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% % Version control history
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% % $Id$
+% % $Log$
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+
+
+% Copyright (c) P.J. Gawthrop, 1998.
+
+% Check that there are exactly two bonds.
+if check_bonds(bonds,2,'EBTF')==0
+  return
+end
+
+% Effort must be imposed by both bonds
+if (bonds(1,1)==-1)|(bonds(2,1)==-1) % Overcausal
+  status = 1;
+  return
+end;
+
+bonds(1,1) = 1; 
+bonds(2,1) = 1;
+
+% Flow bond must have through causality
+if (bonds(1,2)==0)&(bonds(2,2)==0) % Undercausal
+  status = -1;
+  return
+end;
+
+if (bonds(1,2)==bonds(2,2))&(bonds(1,2)!=0) % Overcausal
+  status = 1;
+  return
+end;
+
+%Set flow causality
+if (bonds(1,2)!=0)
+  bonds(2,2) = -bonds(1,2)
+else
+  bonds(1,2) = -bonds(2,2)
+end;
+  
+status = 0;
+
+
+
+
+
+
+

ADDED   mttroot/mtt/lib/comp/simple/EBTF_eqn.m
Index: mttroot/mtt/lib/comp/simple/EBTF_eqn.m
==================================================================
--- /dev/null
+++ mttroot/mtt/lib/comp/simple/EBTF_eqn.m
@@ -0,0 +1,51 @@
+function  structure = EBTF_eqn(name,bond_number,bonds,direction,cr,args, ...
+                            structure,eqnfile);
+
+if nargin<8
+  eqnfile = 'stdout';
+end;
+
+% Check that there are exactly two bonds.
+if check_bonds(bonds,2,'EBTF')==0
+  return
+end
+
+% There are 2 ports; extract the information
+e_1 = bonds(1,1);
+f_1 = bonds(1,2);
+e_2 = bonds(2,1);
+f_2 = bonds(2,2);
+
+
+% Effort -- no equation
+
+% Flow
+effort1_name = varname(name,bond_number(1), 1);
+effort2_name = varname(name,bond_number(2), 1);
+flow1_name = varname(name,bond_number(1), -1);
+flow2_name = varname(name,bond_number(2), -1);
+
+if f_1==-1 %Write flow on port 2
+  fprintf(eqnfile,'%s := (%s/%s)*%s;\n' , ...
+      flow2_name, ...
+      effort1_name, ...
+      effort2_name, ...
+      flow1_name);
+else %Write flow on port 1
+  fprintf(eqnfile,'%s := (%s/%s)*%s;\n' , ...
+      flow1_name, ...
+      effort2_name, ...
+      effort1_name, ...
+      flow2_name);
+end;
+
+ 
+
+
+
+
+
+
+
+
+