Known Issues

The toolbox is in an early stage of development, and as most free software there are no guarantees. See the License for the full explanation.

The author did do his best to make a useful piece of software. In general these are some observations that we have found so far, but the toolbox is likely to be rather buggy. Please consult your common sense for the applicability of the software.

If you find a bug not included here, please contact the author. You can see how in the Contact page.

Dense clusters are not always resolved

The problem arises for two different reasons. If dtail is too small the converged deflated triplets, which may have much smaller singular values than the cluster, will fill up the tail. This will only allow a limited amount of triplets from the cluster to be registered.

Whether this is good a bad is problem dependent. When you want to compute an SVD it is bad, but when solving a linear system it is a desirable behaviour. It may nevertheless be possible to do better than what we currently do in the toolbox.

The base workspace is filled with strange variables

The toolbox uses variables in the base workspace to communicate internally. This is necessary because MATLAB does not allow one to modify a variable passed to a function, without creating a copy of the original variable. Apart from slowing a serious large-scale computation to a crawl, it also use up any available memory and (on 32-bit machines) the entire address-space available to Matlab.

The toolbox uses a scheme called parcels to create a semi-structured organization. Normally these parcels are destroyed when a computation is completed. However, if the user interrupted a computation, it may be necessary to destroy these parcels manually.

BBTools can remove some orphaned parcels using a garbage-collector. Unfortunately, this can only take care of parcels with a life-time limited to a known function. If you created an object (e.g. using bbcount) and did not remove it properly (in this case with bbclear), then you get orphaned variables. You may remove them with clear.