(*^
::[	Information =

	"This is a Mathematica Notebook file.  It contains ASCII text, and can be
	transferred by email, ftp, or other text-file transfer utility.  It should
	be read or edited using a copy of Mathematica or MathReader.  If you 
	received this as email, use your mail application or copy/paste to save 
	everything from the line containing (*^ down to the line containing ^*)
	into a plain text file.  On some systems you may have to give the file a 
	name ending with ".ma" to allow Mathematica to recognize it as a Notebook.
	The line below identifies what version of Mathematica created this file,
	but it can be opened using any other version as well.";

	FrontEndVersion = "Macintosh Mathematica Notebook Front End Version 2.2";

	MacintoshStandardFontEncoding; 
	
	fontset = title, inactive, noPageBreakBelow, nohscroll, preserveAspect, groupLikeTitle, center, M7, bold, L3, e8,  24, "New York"; 
	fontset = subtitle, inactive, noPageBreakBelow, nohscroll, preserveAspect, groupLikeTitle, center, M7, bold, L2, e6,  18, "New York"; 
	fontset = subsubtitle, inactive, noPageBreakBelow, nohscroll, preserveAspect, groupLikeTitle, center, M7, bold, L2, e6,  14, "New York"; 
	fontset = section, inactive, noPageBreakBelow, nohscroll, preserveAspect, groupLikeSection, grayBox, M22, bold, L2, a20,  14, "New York"; 
	fontset = subsection, inactive, noPageBreakBelow, nohscroll, preserveAspect, groupLikeSection, blackBox, M19, bold, L2, a15,  12, "New York"; 
	fontset = subsubsection, inactive, noPageBreakBelow, nohscroll, preserveAspect, groupLikeSection, whiteBox, M18, bold, L2, a12,  10, "New York"; 
	fontset = text, inactive, nohscroll, noKeepOnOnePage, preserveAspect, M7, L2,  12, "New York"; 
	fontset = smalltext, inactive, nohscroll, noKeepOnOnePage, preserveAspect, M7, L2,  10, "New York"; 
	fontset = input, noPageBreakInGroup, nowordwrap, preserveAspect, groupLikeInput, M42, N23, bold, L2,  12, "Courier"; 
	fontset = output, output, inactive, noPageBreakInGroup, nowordwrap, preserveAspect, groupLikeOutput, M42, N23, L2,  12, "Courier"; 
	fontset = message, inactive, noPageBreakInGroup, nowordwrap, preserveAspect, groupLikeOutput, M42, N23, R65535, L2,  12, "Courier"; 
	fontset = print, inactive, noPageBreakInGroup, nowordwrap, preserveAspect, groupLikeOutput, M42, N23, L2,  12, "Courier"; 
	fontset = info, inactive, noPageBreakInGroup, nowordwrap, preserveAspect, groupLikeOutput, M42, N23, L2,  12, "Courier"; 
	fontset = postscript, PostScript, formatAsPostScript, output, inactive, noPageBreakInGroup, nowordwrap, preserveAspect, groupLikeGraphics, M7, l34, w282, h287, L2,  12, "Courier"; 
	fontset = name, inactive, nowordwrap, nohscroll, noKeepOnOnePage, preserveAspect, M7, italic, B65535, L2,  10, "Geneva"; 
	fontset = header, inactive, noKeepOnOnePage, preserveAspect, M7, L2,  10, "Times"; 
	fontset = leftheader, inactive, L2,  10, "Times"; 
	fontset = footer, inactive, noKeepOnOnePage, preserveAspect, center, M7, L2,  12, "Times"; 
	fontset = leftfooter, inactive, center, L2,  12, "Times"; 
	fontset = help, inactive, nohscroll, noKeepOnOnePage, preserveAspect, M7, L2,  10, "Geneva"; 
	fontset = clipboard, inactive, noKeepOnOnePage, preserveAspect, M7, L2,  12, "New York"; 
	fontset = completions, inactive, nowordwrap, noKeepOnOnePage, preserveAspect, M7, L2,  12, "New York"; 
	fontset = special1, inactive, nowordwrap, noKeepOnOnePage, preserveAspect, M7, L2,  12, "New York"; 
	fontset = special2, inactive, nowordwrap, noKeepOnOnePage, preserveAspect, center, M7, L2,  12, "New York"; 
	fontset = special3, inactive, nowordwrap, noKeepOnOnePage, preserveAspect, right, M7, L2,  12, "New York"; 
	fontset = special4, inactive, nowordwrap, noKeepOnOnePage, preserveAspect, M7, L2,  12, "New York"; 
	fontset = special5, inactive, nowordwrap, noKeepOnOnePage, preserveAspect, M7, L2,  12, "New York"; 
	paletteColors = 128; currentKernel; 
]
:[font = input; preserveAspect]
(* Set up the graphics *)
:[font = input; dontPreserveAspect]
lightclock[length_,width_,box_,xstart_,ystart_]:=
Graphics[ { RGBColor[0,0,1],
Rectangle[ {xstart,ystart},
			{xstart+width,ystart+box} ],
Rectangle[ {xstart,ystart+length-box},
			{xstart+width,ystart+length} ],
Line[{ {xstart,ystart+box},
		{xstart,ystart+length-box} }],
Line[{ {xstart+width,ystart+box},
		{xstart+width,ystart+length-box} }]
}]

:[font = input; dontPreserveAspect; startGroup]
frame[xstart_,ystart_,xend_,yend_]:=
Graphics[{ GrayLevel[1],
Point[{xstart,ystart}], Point[{xend,yend}]
}]
:[font = message; inactive; preserveAspect; endGroup]
General::spell1: Possible spelling error: new symbol name "frame"
     is similar to existing symbol "Frame".
:[font = input; dontPreserveAspect]
pulse[x_,y_]:= Graphics[{
RGBColor[0.75,0.75,0], PointSize[0.025], Point[{x,y}]
}]
:[font = input; dontPreserveAspect]
track[x_,y_]:= Graphics[ 
{GrayLevel[0.5], PointSize[0.01], Point[{x,y}] }]
:[font = input; dontPreserveAspect]
(* Stationary Light Clock Animation *)
npics=40; npics2=npics/2; tl={};
Do[ 
If[ t<=npics2, y=0.15+ t 0.7/npics2,
			y= 0.85 -(t-npics2) 0.7/npics2 ];
Show[
frame[0,0,1,1],
lightclock[ 1,.1,.1,0.5,0],
pulse[0.55,y],
tl,
PlotRange->All ] ;
tl=AppendTo[ tl, track[0.55,y] ],

{t,0,npics,1} ]
:[font = input; dontPreserveAspect]
(* Moving Light Clock Animation: 1 tick per screen *)
npics=40; npics2=npics/2; tl={};
Do[ 
x= 0.9 t/npics;
If[ t<=npics2, y=0.15+ t 0.7/npics2,
			y= 0.85 -(t-npics2) 0.7/npics2 ];
Show[
frame[0,0,1,1],
lightclock[ 1,.1,.1,x,0],
pulse[x+0.05,y],
tl,
PlotRange->All ] ;
tl=AppendTo[ tl, track[x+0.05,y] ],

{t,0,npics,1} ]
:[font = input; dontPreserveAspect]
(* Setup graphic of chain of stationary clocks *)
clockchain[length_,width_,box_]:=
Graphics[ {
RGBColor[0,0,1],
Rectangle[ {0.05,0.},{0.05+width,box} ],
Rectangle[ {0.05,length-box},{0.05+width,length} ],
RGBColor[0,0,1],
Line[{ {0.05,box},{0.05,length-box} }],
Line[{ {0.05+width,box},{0.05+width,length-box} }],

RGBColor[0,0,1],
Rectangle[ {0.05+2 width,0.},{0.05+3 width,box} ],
Rectangle[ {0.05+2 width,length-box},{0.05+3 width,length} ],
RGBColor[0,0,1],
Line[{ {0.05+2 width,box},{0.05+2 width,length-box} }],
Line[{ {0.05+3 width,box},{0.05+3 width,length-box} }],

RGBColor[0,0,1],
Rectangle[ {0.05+4 width,0.},{0.05+5 width,box} ],
Rectangle[ {0.05+4 width,length-box},{0.05+5 width,length} ],
RGBColor[0,0,1],
Line[{ {0.05+4 width,box},{0.05+4 width,length-box} }],
Line[{ {0.05+5 width,box},{0.05+5 width,length-box} }],

RGBColor[0,0,1],
Rectangle[ {0.05+6 width,0.},{0.05+7 width,box} ],
Rectangle[ {0.05+6 width,length-box},{0.05+7 width,length} ],
RGBColor[0,0,1],
Line[{ {0.05+6 width,box},{0.05+6 width,length-box} }],
Line[{ {0.05+7 width,box},{0.05+7 width,length-box} }],

RGBColor[0,0,1],
Rectangle[ {0.05+8 width,0.},{0.05+9 width,box} ],
Rectangle[ {0.05+8 width,length-box},{0.05+9 width,length} ],
RGBColor[0,0,1],
Line[{ {0.05+8 width,box},{0.05+8 width,length-box} }],
Line[{ {0.05+9 width,box},{0.05+9 width,length-box} }]

}]

:[font = input; dontPreserveAspect]
(*  light clocks animation: moving and stationary *)
npics=40; npics2=npics/2; npics4=npics/4;
npics34=3 npics/4; tl={};
cchain=clockchain[0.45,0.1,0.1];
Do[ 
x= 0.9 t/npics;
If[ t<=npics2, y=0.675+ t 0.2/npics2,
			y= 0.875 -(t-npics2) 0.2/npics2 ];
			
If[ t<=npics4, ys=0.125+ t 0.2/npics4,
  If[ t<=npics2, ys=0.325-(t-npics4) 0.2/npics4,
    If[ t<=npics34,
    		ys=0.125 +(t-npics2) 0.2/npics4,
    		ys=0.325-(t-npics34) 0.2/npics4 ]
    ]
  ];
  
Show[
frame[0,0,1,1],
lightclock[ 0.45,.1,.1,x,0.55],
pulse[x+0.05,y],
tl,

cchain,
pulse[0.1,ys], pulse[0.3,ys],pulse[0.5,ys],
pulse[0.7,ys],pulse[0.9,ys],

PlotRange->All ] ;
tl=AppendTo[ tl, track[x+0.05,y] ],

{t,0,npics,1} ]
^*)