solution_level_control
Cost estimates associated with a set of solution control values.
Specification
Alias: None
Arguments: STRING
Default: use of single default solution level
Description
Simulation-based models may have an associated solution_level_control
,
which identifies a hierarchy of solution states, such as a set of mesh
discretizations from coarse to fine, a set of solver tolerances from
loose to tight, etc. The string specified as the solution_level_control
identifies a discrete variable label that parameterizes the hierarchy
of solution states.
Note: If the discrete variable identified is a discrete set variable,
then it is important to note that the variable’s set values will be ordered
(lexicographically in the case of string variables), and the ordering
of values provided in solution_level_cost
should correspond to this
set ordering. A common error is to provide a listing of
set values that is out of order and then providing a set of costs
corresponding to this misordered list – in this case, the solution level
costs will be associated with the re-ordered set values.
Examples
In this example, integer solution control values and solution costs are naturally well ordered.
model,
simulation
solution_level_control = 'mesh_size'
solution_level_cost = 1. 8. 64. 512. 4096.
variables,
uniform_uncertain = 9
lower_bounds = 9*-1.
upper_bounds = 9* 1.
discrete_state_set
integer = 1
set_values = 4 8 16 32 64
descriptors = 'mesh_size'
In this example, string solution control values are lexicographically ordered, and care must be taken to align the solution cost estimates.
model,
simulation
solution_level_control = 'mesh_size'
solution_level_cost = 1. 64. 8. # match set ordering
variables,
uniform_uncertain = 9
lower_bounds = 9*-1.
upper_bounds = 9* 1.
discrete_state_set
string = 1
set_values = 'COARSE' 'FINE' 'MEDIUM' # lexicographical ordering
descriptors = 'mesh_size'