Support AMPL files

The following files are useful for several discretized control problems listed on the AMPL Category page. They need to be saved to the same directory.

ampl_general.mod

param T    > 0;     # End time
param nt   > 0;     # Number of discretization points in time
param nu   > 0;     # Number of control discretization points
param nx   > 0;     # Dimension of differential state vector
param ntperu > 0;   # nt / nu
set I:= 0..nt;
set U:= 0..nu-1;
param uidx {I}; param fix_w; param fix_w;
 
var w {U} >= 0, <= 1 binary;    # control function
var dt {U} >= 0, <= T;          # stage length vector

ampl_general.dat

if ( fix_w > 0 )  then { for {i in U} { fix w[i]; } }
if ( fix_dt > 0 ) then { for {i in U} { fix dt[i]; } }
 
# Set indices of controls corresponding to time points
for {i in 0..nu-1} {
  for {j in 0..ntperu-1} { let uidx[i*ntperu+j] := i; }
}
let uidx[nt] := nu-1;

OptimalControl.mod

This header file is required for solving AMPL models of ODE/DAE constrained optimal control problems using a solver that supports the TACO toolkit for AMPL control optimization.

suffix type symbolic IN;
 
option type_table '\
1  u0        piecewise constant control\
2  u1        piecewise linear control\
3  u1c       piecewise linear continuous control\
4  u3        piecewise cubic control\
5  u3c       piecewise cubic continuous control\
6  dae       DAE algebraic state variable\
7  Lagrange  Prevent least-squares detection in an objective\
';
 
function diff;
function eval;
function integral;