# solution_level_cost

Cost estimates associated with a set of solution control values.

**Specification**

*Alias:*None*Arguments:*REALLIST

**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. In algorithms that manage such a hierarchy and
perform optimal resource allocation among the solution states (e.g.,
multilevel Monte Carlo), it is important to estimate a set of costs
associated with each state. These cost estimates can be relative,
such as in the example below (lowest cost normalized to 1.)

*Note:* a scalar solution cost can be specified without an associated
solution level control. This is useful when employing a hierarchy of
model forms (each model has a scalar solution cost and no solution level
control) instead of a hierarchy of discretization levels (one model has
a vector-valued solution cost associated with multiple solution levels).

**Examples**

```
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'
```