edual.m

来自「这是几何代数的matlab工具包」· M 代码 · 共 25 行

function C = Edual(A)
%Edual(A): Computes the dual, A/I3
%
%See also gable.

% GABLE, Copyright (c) 1999, University of Amsterdam
% Copying, use and development for non-commercial purposes permitted.
%          All rights for commercial use reserved; for more information
%          contact Leo Dorst ([e-mail]).
%
%          This software is unsupported.

%The dual is calculated by right multiplication by the inverse of the
% pseudoscalar. In this case we get a negative sign from the grade of 
% the pseudoscalar.
% Conceptually we want
%    T=GAproduct(A,GA([0;0;0;0;0;0;0;-1]));
% but the code is more efficient as
    T = GA([A.m(8);A.m(6);A.m(7);A.m(5);-A.m(4);-A.m(2);-A.m(3);-A.m(1)]);
    if GAautoscalar&isascalar(T)
       C=T.m(1);
    else
       C=T;
    end