ADDED   mttroot/mtt/lib/comp/simple/GY_cause.m
Index: mttroot/mtt/lib/comp/simple/GY_cause.m
==================================================================
--- /dev/null
+++ mttroot/mtt/lib/comp/simple/GY_cause.m
@@ -0,0 +1,30 @@
+function [bonds,status] = GY_cause(bonds);
+% GY_cause - causality for GY component
+% 
+%     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+%     %%%%% Model Transformation Tools %%%%%
+%     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% 
+% Matlab function  GY_cause
+% [bonds,status] = GY_cause(bonds);
+
+%SUMMARY GY: elementary gyrator component
+%DESCRIPTION Energy conserving two-port
+%DESCRIPTION e_1 = f(f_2); f_1 = f(e_2)
+
+
+
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% Version control history
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% $Id$
+% %% $Log$
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+% Copyright (c) P.J. Gawthrop, 1996.
+
+%Causality of GY is same as that of a TF but with flipped effort/flow
+bonds(2,:) = - bonds(2,:);
+[bonds,status] = TF_cause(bonds);
+bonds(2,:) = - bonds(2,:);

ADDED   mttroot/mtt/lib/comp/simple/TF_cause.m
Index: mttroot/mtt/lib/comp/simple/TF_cause.m
==================================================================
--- /dev/null
+++ mttroot/mtt/lib/comp/simple/TF_cause.m
@@ -0,0 +1,27 @@
+function [bonds,status] = TF_cause(bonds);
+% TF_cause - causality for a TF component
+% 
+%     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+%     %%%%% Model Transformation Tools %%%%%
+%     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% 
+% Matlab function  TF_cause
+% [bonds,status] = TF_cause(bonds)
+
+%SUMMARY TF: elementary transformer component
+%DESCRIPTION Energy conserving two-port
+%DESCRIPTION e_1 = f(e_2); f_1 = f(f_2)
+
+
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% Version control history
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% $Id$
+% %% $Log$
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+% Copyright (c) P.J. Gawthrop, 1996.
+
+%Causality of TF is same as that of a junction
+[bonds,status] = zero_cause(bonds);