A fast combinatorial algorithm can significantly reduce the computational
burden when solving general equality and inequality constrained least
squares problems with large numbers of observation vectors. The
combinatorial algorithm provides a mathematically rigorous solution and
operates at great speed by reorganizing the calculations to take
advantage of the combinatorial nature of the problems to be solved. The
combinatorial algorithm exploits the structure that exists in large-scale
problems in order to minimize the number of arithmetic operations
required to obtain a solution.