function DrawSimplex(S,c1,c2)% DrawSimplex(S,c1,c2): draw a simplex S using colors c1 and c2%  S is a cell array of 1,2,or 3 vectors.%  c1 is the color of the vectors in S%  c2 is the color of the simplex spanned by S%  c1 and c2 are optional, although c1 must be specified if c2 is used%  If c1=='n', then the vectors of S are not drawn.%%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 (leo@wins.uva.nl).%%          This software is unsupported.if nargin == 1    c1 = 'b';    c2 = 'y';elseif nargin == 2    c2 = 'y';elseif nargin ~= 3    error('DrawSimplex takes no more than 3 arguments');endif length(S)==1    if ~strcmp(c1,'n')	draw(S{1},GA,c1);    end    dx = inner(e1,S{1});    dy = inner(e2,S{1});    dz = inner(e3,S{1});    sc = 0.01*sqrt(abs(norm(S{1})));    x = sc*[-1 -1 -1 -1]+dx;    y = sc*[-1  1  1 -1]+dy;    z = sc*[-1 -1  1  1]+dz;    patch(x,y,z,c2,'EdgeColor','none');    x = sc*[ 1  1  1  1]+dx;    y = sc*[-1  1  1 -1]+dy;    z = sc*[-1 -1  1  1]+dz;    patch(x,y,z,c2,'EdgeColor','none');    y = sc*[-1 -1 -1 -1]+dy;    x = sc*[-1  1  1 -1]+dx;    z = sc*[-1 -1  1  1]+dz;    patch(x,y,z,c2,'EdgeColor','none');    y = sc*[ 1  1  1  1]+dy;    x = sc*[-1  1  1 -1]+dx;    z = sc*[-1 -1  1  1]+dz;    patch(x,y,z,c2,'EdgeColor','none');    z = sc*[-1 -1 -1 -1]+dz;    y = sc*[-1  1  1 -1]+dy;    x = sc*[-1 -1  1  1]+dx;    patch(x,y,z,c2,'EdgeColor','none');    z = sc*[ 1  1  1  1]+dz;    y = sc*[-1  1  1 -1]+dy;    x = sc*[-1 -1  1  1]+dx;    patch(x,y,z,c2,'EdgeColor','none');    axis tight;elseif length(S)==2    if ~strcmp(c1,'n')        draw(S{1},GA,c1);        draw(S{2},GA,c1);    end    DrawPolyline({.5*(S{2}-S{1})+S{1},S{2}},c2);    draw(.5*(S{2}-S{1}),S{1},c2);elseif length(S)==3    if ~strcmp(c1,'n')        draw(S{1},GA,c1);        draw(S{2},GA,c1);        draw(S{3},GA,c1);    end    DrawPolygon(S,c2);    P = (S{2}-S{1})^(S{3}-S{2});	% plane of triangle    P = P/norm(P);    e1v = S{2}-S{1};    e1p = P*e1v;	% rotate e1p by 90 degrees    DrawPolyline({.5*e1v+S{1},.4*e1v+S{1}+.05*e1p},'k');    e2v = S{3}-S{2};    e2p = P*e2v;	% rotate e2p by 90 degrees    DrawPolyline({.5*e2v+S{2},.4*e2v+S{2}+.05*e2p},'k');    e3v = S{1}-S{3};    e3p = P*e3v;	% rotate e3p by 90 degrees    DrawPolyline({.5*e3v+S{3},.4*e3v+S{3}+.05*e3p},'k');endaxis equal;hold on;