Incomplete Labelling Information is not saved

Update June 2005: ViewHAR now works around the problem described below. The workaround is: matrices which have dimensions without sets attached now are stored on file with dummy sets attached to the unlabelled dimensions. For example, a matrix with dimensions COM*22 is stored on file with dimensions COM*UNK22, where UNK22 (unknown 22) is an artificial set created for the purpose. Conversely, when ViewHAR reads from disk a matrix with dimensions COM*UNK22, the matrix is converted to dimensions COM*22. Hence, dummy sets (like UNK22) are not visible while in ViewHAR.

////////// Information below relates to previous ViewHAR versions //////////

GEMPACK allows real matrices to have sets associated with all dimensions, or with no dimensions. But it does not allow some only of the dimensions to be associated with a set. For example, according to GEMPACK, a matrix can be of dimensions COM*IND or 22*19 but not COM*19 or 22*IND. Such partially labelled matrices may arise during a ViewHAR session if you begin attaching set labels to an un-labelled real matrix, but do not complete the task. If you then attempt to save the file as a header array file, such incompletely labelled matrices are stored on disk with no labels or coefficient names. For example, a matrix dimensioned COM*19 would be saved as 22*19. If that happens, a warning is posted.

The coefficient name is also part of the data that GEMPACK stores with set labels. Unless set labels are attached to every dimension of a vector or matrix, the coefficient name will not be stored on disk. This even applies to vectors with just one element (see scalars).

You will be warned if ViewHAR discards incomplete labelling information when saving a file to disk. However, if the file is still open the incomplete labelling information is still preserved in memory. Therefore, you may be able to complete the labelling information by attaching set labels, then save again.

URL of this topic: www.copsmodels.com/webhelp/viewhar/hc_labslost.htm

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