# algebraic_mappings

Use AMPL to define algebraic input-output mappings

**Specification**

*Alias:*None*Arguments:*STRING*Default:*no algebraic mappings

**Description**

Dakota can evaluate algebraic input-output mappings using AMPL
[FGK03]. The mappings are expressed in 3 files: `stub`

.nl,
`stub`

.col, and `col,stub`

.row, where `row,stub`

is a particular root name
describing a particular problem. The file names are communicated to
Dakota using the `algebraic_mappings`

keyword. It may either specify
the full `stub`

.nl filename, or alternatively, just the `nlstub`

basename.

Dakota then extracts the input and output identifier strings from
`stub`

.col and `colstub`

.row and employs the AMPL solver library [Gay97]
to process the directed acyclic graphc (DAG) specification in
`stub`

.nl. The variable and objective function names declared within
AMPL should be a subset of the variable and response descriptors
specified in the `variables`

and `responses`

blocks. Ordering is
not important, as Dakota will reorder data as needed.

**Examples**

An interface employing both algebraic and simulation-based mappings. The results from the individual algebraic and simulation mappings are overlaid based on the variable and response descriptors used by the individual mappings.

```
interface,
algebraic_mappings = 'ampl/fma.nl'
fork
analysis_driver = 'text_book'
parameters_file = 'tb.in'
results_file = 'tb.out'
```