The SifDec package is distributed with three default ``sizes'': large, medium, and small. In addition, there is a custom size, which, as the term indicates, may be suitable for situations demanding a specialized configuration. These sizes refer to the size of the memory available for problem decoding and solution, and hence are directly related to the size (the amount of data) of the problems that SifDec can tackle. It may happen that the predetermined sizes do not fit your favorite problem or your machine, and that you wish to specify your own. Typically, when running too large a problem, SifDec will complain that one of the size parameters is too small and stop. You then have to increase this parameter (if this is possible on your machine) in order to handle the problem. This modification of the SifDec array sizes is explained below.
The actual choice of one of the predetermined sizes is made when running the install_sifdec command, which prompts the user for the desired size. In fact, install_sifdec, or the Makefiles, depending on which SifDec you are using, cast the source code against a ``size mask'' corresponding to the selected size, and thereby determines the dimensions of the various arrays used in the code. The assignment statements are differentiated by their first four characters:
| CBIG | specifies the large size |
| CMED | the medium size |
| CTOY | the small size |
| CCUS | the custom size |
Note that the custom size is first thought of as larger than the large size, but nothing prevents the user from building an intermediary size or a smaller size than the toy size.
Changing the size of the SifDec distribution in the sense just described may call for a partial re-installation. If most (or all) parameters must be, say, increased, it might be worth considering simply re-installing SifDec using a larger size (e.g. large if medium turns out to be insufficient for your purposes). To that end, execute install_sifdec again and select the correct size. In case very few parameters need to be changed, the procedure described below might be considered. We now examine this procedure in more detail.