FEMGEN User Routines

Chapter 2 details the use of individual FEMGEN User Routines. The routines are used to access the FEMGEN database and may thus be called in any order. For external interfaces routine USTRT2 must be called to open the database, and routine UCLOS to close it; for internal interfaces FEMGEN performs these operations and the calls to USTRT2 and UCLOS are not needed. Note that internal interfaces must adhere to the conventions detailed in Chapter 3 and that the use of such interfaces is controlled by the FEMGV keyfile and are activated via the FEMGEN command 'UTILITY WRITE name'.

Whether an internal or external interface is developed the first FEMGEN User Routine to be called will usually be routine USIZE. This routine gives key model information such as the number of points, lines etc. which is then used as a basis for making enquiries to the FEMGEN database using the other routines. Note that the number of each type of entity which USIZE returns are the maximum identification numbers in the model and that (due to deletions) some of the intermediate identification numbers may not exist.

For example; if one wished to find all of the nodes in the model one would make a call to routine USIZE to determine the maximum node number, and then loop from 1 to this number calling subroutine UNODE for all possible nodes. Routine UNODE will either return the nodal coordinates or an error code indicating that the node does not exist. Appendix A gives an example of an external interface program.