# Software Limitations and Bugs

The ALADDIN software package is still in development. Here is a list of software limitations and bugs that we know about:

If you find a programming error, or a component of the software that has not been implemented (and should have been), please let us know by sending E-mail to austin@isr.umd.edu.

### MATRIX PACKAGE

• The matrix function PrintMatrixCast() works for statements of the type
```        PrintMatrixCast ( A, [cm]);
```
where the units conversion is a built-in name. We need to extend the language so that commands of the type
```        PrintMatrixCast ( A, [cm/sec/sec] );
```
will also work.

• When the Stiff() function is used to compute a finite element stiffness matrix, as in:
```        stiff = Stiff();
```
ALADDIN will return a global stiffness matrix stored in skyline storage. We currently assume that the stiffness matrix will be symmetric (although some applications will lead to non-symmetric matices).

It is conceivable that with the stiffness matrix in hand, some users may wish to modify its contents will statements of the type:
```        stiff  = 10^10 N/m;
```
Assignments of this type are not supported because they will destroy the matrix symmetry.

### FINITE ELEMENT LIBRARY

• So far we have only implemented units computations in the 2-D and 3-D beam finite elements. Units computations are missing from the plane-stress/plane-strain element, the four node shell element (with drilling d.o.f.), and the plate finite element.

• Mass matrix computations are missing from the four node shell element (with drilling d.o.f.), and the plate finite element.

• The GetDispl() and GetStress() functions have only been implemented in the 2-D and 3-D beam finite elements.

We are currently adding these functions to the plane stress/plane strain elements.

• We suspect there is a small bug in the plane stress/plane strain element. This is being checked out, and we will present example web pages and the corrected element soon (i.e., before the end of July 1997).

• The DQK plate element needs to be checked for accuracy of numerical results (see elmt_plate.c).

If you decide to add/fix some of these features, please e-mail austin@isr.umd.edu, and we will get you the appropriate code to work on.

Developed in April 1996 by Mark Austin