Function GMP::Instance::GetColumnNumbers(GMP, variableSet)

# GMP::Instance::GetColumnNumbers

The function `GMP::Instance::GetColumnNumbers` returns a subset of the column numbers of a generated mathematical program. It returns the column numbers that are generated for a set of variables.

```GMP::Instance::GetColumnNumbers(
GMP,                ! (input) a generated mathematical program
variableSet,        ! (input) a set of variables
)
```

## Arguments

GMP

An element in the set `AllGeneratedMathematicalPrograms`.

variableSet

A subset of the set `AllVariables`.

## Return Value

The function returns a subset of the column numbers as a subset of the set `Integers`.

## Example

Assume we have generated a mathematical program and we want to change the upper bound of the variables `demand(i)` and `supply(j,k)` into 100. This can be done as follows:

```myGMP := GMP::Instance::Generated( MP );

for (i) do
GMP::Column::SetUpperBound( myGMP, demand(i), 100 );
endfor;

for (j,k) do
GMP::Column::SetUpperBound( myGMP, supply(j,k), 100 );
endfor;
```

Using the function `GMP::Instance::GetColumnNumbers` this can also be coded as follows. Here `ColNrs` is a subset of `Integers` with index `c`, and `Vars` a subset of `AllVariables`.

```myGMP := GMP::Instance::Generated( MP );

Vars := { 'demand', 'supply' };

ColNrs := GMP::Instance::GetColumnNumbers( myGMP, Vars );

for (c) do
GMP::Column::SetUpperBound( myGMP, c, 100 );
endfor;
```