67.4 Basic conventions employed in matrix package

A G-module is defined by the action of a group G, generated by a set of matrices, on a d-dimensional vector space over a field, F = GF(q).

The function GModule returns a G-module record, where the component .field is set to F, .dimension to d, .generators to the set of generating matrices for G, and .isGModule to true. These components are set for every G-module record constructed using GModule.

Many of the functions described below return or update a G-module record. Additional components which describe the nature of the action of the underlying group G on the G-module are set by these functions. Some of these carry information which may be of general use. These components are described briefly in Components of a $G$-module record. They need not appear in a G-module record, or may have the value "unknown".

A component .component of a G-module record is accessed by ComponentFlag and its value is set by SetComponentFlag, where the first letter of the component is capitalised in the function names. For example, the component .tensorBasis of module is set by SetTensorBasisFlag( module, boolean ) and its value accessed by TensorBasisFlag( module ). Such access functions and conventions also apply to other records constructed by all of these functions.

If a function listed below takes as input a matrix group G, it also usually accepts a G-module.

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GAP 3.4.4
April 1997