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add a minimal matrix rep
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‎lib/matobjminimal.gd

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#############################################################################
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##
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## This file is part of GAP, a system for computational discrete algebra.
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##
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## SPDX-License-Identifier: GPL-2.0-or-later
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##
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## Copyright of GAP belongs to its developers, whose names are too numerous
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## to list here. Please refer to the COPYRIGHT file for details.
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##
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############################################################################
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#
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# This is a minimal implementation for nxm matrices
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# stored as a flat n*m element list. In this
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# file the representation, types and global
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# functions are declared.
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# This implementation should not be used for actual computations. It serves
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# as an example for a minimal MatrixObj implementation and can be used to test
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# various things.
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#############################################################################
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##
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## <#GAPDoc Label="IsMinimalExampleMatrixRep">
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## <ManSection>
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## <Filt Name="IsMinimalExampleMatrixRep" Arg='obj' Type="representation"/>
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##
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## <Description>
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## An object <A>obj</A> in <Ref Filt="IsMinimalExampleMatrixRep"/> describes
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## a matrix object that stores the matrix entries as a flat list. It is
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## internally represented as a positional object
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## (see <Ref Filt="IsPositionalObjectRep"/> that stores 4 entries:
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## <Enum>
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## <Item>
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## its base domain
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## (see <Ref Attr="BaseDomain" Label="for a matrix object"/>),
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## </Item>
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## <Item>
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## the number of rows (see <Ref Attr="NumberRows" Label="for a matrix object"/>),
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## </Item>
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## <Item>
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## the number of columns
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## (see <Ref Attr="NumberColumns" Label="for a matrix object"/>), and
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## </Item>
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## <Item>
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## a plain list (see <Ref Filt="IsPlistRep"/> of its entries.
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## </Item>
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## </Enum>
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## It implements the MatrixObj specification in a minimal way, that is it
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## implements exactly the required methods. This is intended for testing and
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## development and should not be used for actual calculations!
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## </Description>
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## </ManSection>
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## <#/GAPDoc>
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##
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# Here we declare the new representation and tell GAP which properties it
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# implies. FListMatrices e.g. are positional objects and so on.
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DeclareRepresentation( "IsMinimalExampleMatrixRep",
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IsMatrixObj and IsMatrixOrMatrixObj and IsPositionalObjectRep
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and IsNoImmediateMethodsObject
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and HasNumberRows and HasNumberColumns
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and HasBaseDomain and HasOneOfBaseDomain and HasZeroOfBaseDomain,
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[] );
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# If we implement our object as a positional object we often have to access its
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# properties in the code. To make that more readable we declare global
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# variables. If you do this too make sure you use variables that are unique and
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# unlikely to be used someplace else, even though that might mean using longer
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# names. Here we prefixed the names with the name of the representation. See
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# also Reference Manual Chapter 79 for more information about Objects.
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# Some constants for matrix access:
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# Position in the positional object of the base domain
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BindGlobal( "MINREP_BDPOS", 1 );
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# Position in the positional object of the number of rows
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BindGlobal( "MINREP_NRPOS", 2 );
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# Position in the positional object of the number of columns
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BindGlobal( "MINREP_NCPOS", 3 );
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# Position in the positional object of the list of entries
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BindGlobal( "MINREP_ELSPOS", 4 );

‎lib/matobjminimal.gi

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#############################################################################
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##
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## This file is part of GAP, a system for computational discrete algebra.
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##
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## SPDX-License-Identifier: GPL-2.0-or-later
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##
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## Copyright of GAP belongs to its developers, whose names are too numerous
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## to list here. Please refer to the COPYRIGHT file for details.
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##
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############################################################################
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#
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# This file is a minimal implementation for new style vectors and matrices.
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# It stores matrices as a dense flat list.
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# This implementation implements only the methods required by the specification
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# for matrix objects. This is intended for testing.
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InstallMethod( NewMatrix,
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"for IsMinimalExampleMatrixRep, a ring, an int, and a list",
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[ IsMinimalExampleMatrixRep, IsRing, IsInt, IsList ],
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function( filter, basedomain, nrcols, list_in )
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local obj, filter2, list, rowindex, colindex;
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# If applicable then replace a nested list 'list_in' by a flat list 'list'.
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if Length(list_in) > 0 and (IsVectorObj(list_in[1]) or IsList(list_in[1])) then
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list := [];
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for rowindex in [1..Length(list_in)] do
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if Length(list_in[rowindex]) <> nrcols then
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Error( "NewMatrix: Each row must have nrcols entries." );
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fi;
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for colindex in [1..nrcols] do
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list[(rowindex-1)*nrcols + colindex] := list_in[rowindex][colindex];
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od;
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od;
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else
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if Length(list_in) mod nrcols <> 0 then
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Error( "NewMatrix: Length of list must be a multiple of ncols." );
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fi;
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list := list_in;
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fi;
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obj := [basedomain,Length(list)/nrcols,nrcols,list];
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filter2 := IsMinimalExampleMatrixRep and IsMutable;
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if HasCanEasilyCompareElements(Representative(basedomain)) and
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CanEasilyCompareElements(Representative(basedomain)) then
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filter2 := filter2 and CanEasilyCompareElements;
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fi;
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Objectify( NewType(CollectionsFamily(FamilyObj(basedomain)),
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filter2), obj);
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return obj;
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end );
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InstallMethod( BaseDomain, "for a minimal example matrix rep",
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[ IsMinimalExampleMatrixRep ],
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function( m )
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return m![MINREP_BDPOS];
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end );
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InstallMethod( NumberRows, "for a minimal example matrix rep",
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[ IsMinimalExampleMatrixRep ],
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function( m )
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return m![MINREP_NRPOS];
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end );
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InstallMethod( NumberColumns, "for a minimal example matrix rep",
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[ IsMinimalExampleMatrixRep ],
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function( m )
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return m![MINREP_NCPOS];
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end );
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InstallMethod( MatElm, "for an minimal example matrix rep and two positions",
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[ IsMinimalExampleMatrixRep, IsPosInt, IsPosInt ],
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function( mat, row, col )
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return mat![MINREP_ELSPOS][(row-1)*mat![MINREP_NCPOS]+col];
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end );
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InstallMethod( SetMatElm, "for an minimal example matrix rep, two positions, and an object",
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[ IsMinimalExampleMatrixRep and IsMutable, IsPosInt, IsPosInt, IsObject ],
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function( mat, row, col, obj )
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mat![MINREP_ELSPOS][(row-1)*mat![MINREP_NCPOS]+col] := obj;
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end );
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InstallMethod( \<, "for two minimal example matrices",
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[ IsMinimalExampleMatrixRep, IsMinimalExampleMatrixRep ],
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function( a, b )
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return LT_LIST_LIST_DEFAULT(a![MINREP_ELSPOS],b![MINREP_ELSPOS]);
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end );
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InstallMethod( ConstructingFilter, "for a minimal example matrix rep",
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[ IsMinimalExampleMatrixRep ],
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function( mat )
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return IsMinimalExampleMatrixRep;
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end );
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InstallMethod( CompatibleVectorFilter, [ IsMinimalExampleMatrixRep ],
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M -> IsPlistVectorRep );

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