# MaximumGap3D

## Syntax

```
constraint MaximumGap3D (1) (2) (3) (4)
# (1) int, unique constraint tag
# (2) int, node tag
# (3) int, node tag
# (4) double, gap
```

## Theory

This is a conditional constraint that limits the distance between two nodes, viz.,

$$
\left|\mathbf{d}\_i+\mathbf{u}\_i-\mathbf{d}\_j-\mathbf{u}*j\right|\leq{}D*{max}.
$$

The participating DoFs are `1`, `2` and `3`.
