DDLab has a function consistencycheck.m that checks the self-consistency of the input dislocation structure before starting the DD simulation. The function consistencycheck.m is called near the very beginning of dd3d.m

This function checks not only the input structures rn and links but also the auxiliary data structures connectivity and linksinconnect, which are created by function genconnectivity.m.

In the version ddlab-2007-12-18.tar.gz or newer, the consistencycheck.m does the following checks. Items 3, 4, 5 are general checks that are in principle necessary for any DD simulation program. Other items are specific to the DDLab data structure and algorithm implementation.

1. the length of the connectivity matrix should be the same as that of links

2. connectivity matrix: each row correspond to a node, 
   only the first 2*numNbrs+1 entries in each row can be non-zero
   where numNbrs is the number of neighbors for this node

3. Burgers vector conservation at every node (if flag != 7)

4. a node cannot be connected to another node twice

5. a link cannot have zero Burgers vector

6. a node cannot be connected to the same link twice in the connectivity matrix

7. consistency between "connectivity" matrix and "links" matrix
   if node i has a link j, then link j must have node i as one of its end nodes

8. check the consistency between the "connectivity" matrix and the "linkinconnect" matrix