map2arg.gi

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#W  map2arg.gi                   XMOD Package                    Chris Wensley
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#Y  Copyright (C) 2001-2016, Chris Wensley et al,  
#Y  School of Computer Science, Bangor University, U.K. 

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#F  Mapping2ArgumentsByFunction( <D>, <E>, <fun> ) . create map from function
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InstallGlobalFunction( Mapping2ArgumentsByFunction, 
function ( arg )
    local  map; 

    if not ( Length( arg ) = 3 ) then
        Error( "usage: Mapping2ArgumentsByFunction( <[D1,D2]>, <E>, <fun> )" );
    fi;
    # ensure that the entries in source and the range are domains
    if not ( IsList(arg[1]) and IsDomain(arg[1][1]) 
             and IsDomain(arg[1][2]) and IsDomain(arg[2]) ) then
	 Error("Mapping2ArgumentsByFunction: Source[1,2], Range not domains");
    fi;

    # make the general mapping
    map:= Objectify( TypeOfDefaultGeneralMapping( arg[1], arg[2],
                             IsNonSPMappingByFunctionRep
                         and IsSingleValued
                         and IsTotal ),
                       rec( fun := arg[3] ) );
    SetIsMapping2ArgumentsByFunction( map, true );
    # deleted code re inverses
    return map;
end );

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#M  ImageElm( <map>, <elm> )  . . . . . . . . . . . . for mapping by function
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InstallMethod( ImageElm, "for mapping by function", true, 
    [ IsMapping2ArgumentsByFunction, IsList ], 0,
function ( map, elm )
    return map!.fun( elm );
end );

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#E map2arg.gi . . . . . . . . . . . . . . . . . . . . . . . . . . . ends here