ADDED   mttroot/mtt/lib/cr/r/MA.cr
Index: mttroot/mtt/lib/cr/r/MA.cr
==================================================================
--- mttroot/mtt/lib/cr/r/MA.cr
+++ mttroot/mtt/lib/cr/r/MA.cr
@@ -0,0 +1,89 @@
+%SUMMARY MA: Mass-action kinetics for Re
+%DESCRIPTION Parameter 1: kappa
+
+OPERATOR MA;
+
+%%% Two port version (standard)
+FOR ALL n_out, A_f, A_r, kappa
+LET MA(R, flow,kappa,flow,n_out,	
+   A_f,effort,1,	
+   A_r,effort,2) = kappa*(exp(A_f/RT) - exp(A_r/RT));
+
+
+%%% Four port version (stoichiometric) with integral causality
+%% Flows on ports 1 & 2 = flow on port 3.
+FOR ALL A_f, A_r, v_1, v_2,kappa
+LET MA(R, flow,kappa,flow,1,	
+   A_f,effort,1,	
+   A_r,effort,2,
+   v_1,flow,3,
+   v_2,effort,4) = v_1;
+
+FOR ALL A_f, A_r, v_1, v_2,kappa
+LET MA(R, flow,kappa,flow,2,	
+   A_f,effort,1,	
+   A_r,effort,2,
+   v_1,flow,3,
+   v_2,effort,4) = v_1;
+
+%% Flow on port 4 is induced flow
+FOR ALL A_f, A_r, v_1, v_2,kappa
+LET MA(R, flow,kappa,flow,4,	
+   A_f,effort,1,	
+   A_r,effort,2,
+   v_1,flow,3,
+   v_2,effort,4) = kappa*(exp(A_f/RT) - exp(A_r/RT));
+
+%%% Four port version (stoichiometric) with flow imposed on port 1
+%% Flow on port 2 = flow on port 1
+FOR ALL A_1,A_2,A_3,A_4, v_1,v_2,v_3,v_4, kappa
+LET MA(R, flow,kappa,flow,2,	
+   v_1,flow,1,	
+   A_2,effort,2,
+   v_3,flow,3,
+   A_4,effort,4) = v_1;
+
+%% Flow on port 4 = flow on port 1
+FOR ALL A_1,A_2,A_3,A_4, v_1,v_2,v_3,v_4, kappa
+LET MA(R, flow,kappa,flow,4,	
+   v_1,flow,1,	
+   A_2,effort,2,
+   v_3,flow,3,
+   A_4,effort,4) = v_1;
+
+%% Effort on port 1
+FOR ALL A_1,A_2,A_3,A_4,v_1,v_2,v_3,v_4,kappa
+LET MA(R,flow,kappa,effort,1,
+   v_1,flow,1,	
+   A_2,effort,2,
+   v_3,flow,3,
+   A_4,effort,4) = RT*log( (v_1/kappa) + exp(A_2/RT) );
+
+
+%%% Four port version (stoichiometric) with flow imposed on port 2
+
+%% Flow on port 1 = flow on port 2
+FOR ALL A_1,A_2,A_3,A_4, v_1,v_2,v_3,v_4, kappa
+LET MA(R, flow,kappa,flow,1,	
+   A_1,effort,1,	
+   v_2,flow,2,
+   v_3,flow,3,
+   A_4,effort,4) = v_2;
+
+%% Flow on port 4 = flow on port 2
+FOR ALL A_1,A_2,A_3,A_4, v_1,v_2,v_3,v_4, kappa
+LET MA(R, flow,kappa,flow,4,	
+   A_1,effort,1,	
+   v_2,flow,2,
+   v_3,flow,3,
+   A_4,effort,4) = v_2;
+
+%% Effort on port 2
+FOR ALL A_1,A_2,A_3,A_4,v_1,v_2,v_3,v_4,kappa
+LET MA(R,flow,kappa,effort,2,
+   A_1,effort,1,	
+   v_2,flow,2,
+   v_3,flow,3,
+   A_4,effort,4) = RT*log( (v_2/kappa) + exp(A_1/RT) );
+
+