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FastLinAlg :: regularInCodimension(...,Strategy=>...)

regularInCodimension(...,Strategy=>...) -- strategies for choosing submatrices

Description

Many of the core functions of this package allow the user to fine tune the strategy of how submatrices are selected. Different strategies yield markedly different performance or results on these examples. These are controlled by specifying a Strategy => option, pointing to a HashTable. This HashTable should have the following keys. Each such key should point to an integer.

Functions such as chooseGoodMinors will select a number of random submatrices based on the values of those keys. For example, if LexSmallest and LexLargest are set to 50 approximately the submatrics will be smallest with respect to Lex and the other half will be largest with respect to Lex.The values do not need to add up to 100.

These functions all work by finding the optimal entry with respect to the given strategy, removing that row and column, and then choosing the next optimal entry. This is done until a submatrix of the desired size has been found.

In some functions, the GRevLex versions of this strategy will modify the working matrix in a loop, repeatedly lowering/raising the degree of elementsso as to ensure that different choices are made.

This package comes with several default strategies exported to the user. Additionally, a MutableHashTable named StrategyCurrent is also exported. It begins as the default strategy, but the user can modify it.

Further information

Functions with optional argument named Strategy :