Reordering Columns for Smaller Indexes

A Survey for the Selection of Control Structure for Distillation Columns Based on Steady State Controllability Indexes

Sorting improves word-aligned bitmap indexes

Bitmap indexes must be compressed to reduce input/output costs and minimize CPU usage. To accelerate logical operations (AND, OR, XOR) over bitmaps, we use techniques based on run-length encoding (RLE), such as Word-Aligned Hybrid (WAH) compression. These techniques are sensitive to the order of the rows: a simple lexicographical sort can divide the index size by 9 and make indexes several time...

Evaluation of Some Reordering Techniques for Image VQ Index Compression

Frequently, it is observed that the sequence of indexes generated by a vector quantizer (VQ) contains a high degree of correlation, and, therefore, can be further compressed using lossless data compression techniques. In this paper, we address the problem of codebook reordering regarding the compression of the image of VQ indexes by general purpose lossless image coding methods, such as JPEG-LS...

Efficient Reordering for Direct Methods in Analog Circuit Simulation

For linear systems of equations arising from circuit simulation, we studied the efficiency of the reordering algorithm integrated in the MA27 subroutine package from Duff and Reid. Our conclusion is that the algorithm performs extraordinarily well, provided that the nearly-dense rows and columns of the matrix have been removed prior to reordering. Thus, we recommend the reordering implementatio...

A new technique for the Simplex basis LU factorization update

The objective of this work is to develop more efficient alternatives for Simplex method implementation. Techniques of the Simplex basis LU factorization update are developed to improve the solution of the Simplex method linear systems to achieve a column static reordering of the matrix. A simulation of the Simplex method is implemented, with the change of basis obtained from MINOS. Only the fac...