These are AMPL scripts for nonlinear optimization problems from the paper:

 H. Maurer and H. D. Mittelmann, Optimization Techniques for Solving Elliptic
 Control Problems with Control and State Constraints.
 Part 2: Distributed Control, Comp. Optim. Applic. 18, 141-160 (2001).


Characteristics of the problems
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Notation: RHS:   right-hand side of PDE
          BC:    boundary condition
          CC/SC: control/state constraints
          NOREG: no regularization (zero factor with integral over control)
          OP:    nature of optimization problem

All examples:    Dsitributed Control, neg. Laplacian as differential op.
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  Examples 1-3:  Dirichlet BC, OP: NLP
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Example 1: RHS cubic, Ginzburg-Landau model of superconductivity

Example 2: same as Ex.1, except NOREG, bang-bang control

Example 3: RHS exponential, well-posedness not guaranteed


  Examples 4-6:  Neumann/Mixed BC
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Example 4: RHS exponential, CC/SC both active

Example 5: same as Ex. 4, except NOREG, bang-bang control

Example 6: logistic type, from population dynamics, non-convex objective