Parabola


	

         .................Y=Xsq divided by 4f.................
                            f=focal length
	 example...f=27in......x        y
			       0        0
			       4      .148
			       8      .593
			       12    1.333
			       16    2.370
			       20    3.704
			       24    5.333
			       28    7.259
			       32    9.481
			       36    12.00
		     This is for a 36 inch reflector