## `solvelib::Union` -- union of a system of sets

#### Introduction

`solvelib::Union``(set, param, paramset)` returns the set of all objects that can be obtained by replacing, in some element of `set`, the free parameter `param` by an element of `paramset`.

#### Call(s)

`solvelib::Union(set, param, paramset)`

#### Parameters

`set` | - | set of any type
`param` | - | identifier
`paramset` | - | set of any type

#### Returns

`solvelib::Union` returns a set of any type; see `solve` for an overview of the different types of sets. It may also return the unevaluated call if the union could not be computed.

### Overloadable:

`set`

#### Related Functions

`solve`

#### Details

- `set` may be a set of any type; it need not depend on the parameter `param`, and it may also contain other free parameters. However, it must not use `param` as a bound parameter, e.g. `Dom::ImageSet(sin(param), param, S)` (for some set `S`) .
- `paramset` may be a set of any type and may depend on some free parameters. See example 1.
- If `paramset` is empty, the result is the empty set. Overloading has no effect in this case.

#### Example 1

We compute the set of all numbers that are equal to k+1 or k+3 for k=2, k=4, or k=l, where l is a free parameter.

    >> solvelib::Union({k+1, k+3}, k, {2,4,l});

                              {3, 5, 7, l + 1, l + 3}

#### Changes

- new function

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