Rename hint.txt and hint.text to README.md

2005/persano/README.md

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+# Best of show
+
+Mauro Persano
+São Paulo
+Brazil
+mauro_persano@yahoo.com
+
+## Judges' Comments
+
+### To build
+
+        cc -lm persano.c -o persano
+
+If your system is one of those that distinguish between text and binary
+streams, you must know what to do to switch the standard output into
+binary mode (e.g. adding a line to the source code or specifying a
+linker option).
+
+### Try
+
+        persano 3 16 > knot3-16.gif
+
+Open the GIF file with a viewer capable of displaying animated GIFs and
+watch closely at the bottom of the picture (you may need to use
+"gifsicle" - a great tool to manipulate animated GIFs - to slow down the
+animation and to compress the GIFs generated by the entry).
+
+What needs to be done to fix the problem?
+
+Solving the author's exercises below may or may not help.
+
+At the time of judging, the approximation of π used in the program could
+not be found on mathworld.com.
+
+## Selected Author's Comments
+
+### NAME
+
+**knot**
+> writes animated GIF images of rendered torus knots to standard output.
+
+### SYNOPSIS
+
+        knot p q [num frames]
+
+### DESCRIPTION
+
+A (p,q)-torus knot is a closed, non-intersecting curve on the surface of
+a torus in R3 that winds p times around one cycle of the torus and q
+times around the other. p and q should be coprime; otherwise, the
+resulting curve will _not_ be a knot (that is, imagining the resulting
+curve as a loop of rubber, there will be a way to bend, twist and
+stretch it, without cutting it [1], until it ends up looking just like a
+circle embedded in R3 [2]).
+
+Sample usage:
+
+        knot 3 2 1 > foo.gif
+
+writes a non-animated GIF (a single frame) stream of a rendered trefoil
+knot to the file foo.gif.
+
+        knot 5 2
+
+writes a GIF stream with a rendering of Solomon's Seal knot to standard
+output; since the number of frames is not specified, an animation with
+40 frames will be written.
+
+Please view the code with 8-character tabs!
+
+### OUTPUT FORMAT
+
+The program writes fully valid GIF 89 streams.
+
+It is suggested that the output be viewed with a program capable of
+displaying animated GIFs, such as almost any graphical HTTP browser.
+
+Due to code size constraints, full LZW compression was not implemented
+[3]. In fact, the output images are even somewhat expanded, thanks to
+GIF overhead.
+
+The GIF format supports only a limited number of bits per pixel, so the
+program uses ordered dithering to emulate full RGB output.
+
+### PORTABILITY
+
+The program was tested on Linux, with gcc 3.1; Cygwin, with gcc 3.3; and
+Solaris/Sparc, with Sun's C compiler.
+
+The only major portability issue should be reliance on ASCII.
+
+It should also be mentioned that the program won't work on systems that
+distinguish between text and binary streams; however, since hardly
+anyone uses such systems in this day and age, this is a minor issue. [4]
+
+### EXERCISES FOR THE READER
+
+  1. (1 point) The surface is composed of many small polygons. Try to make it
+smoother by increasing the number of polygons.
+
+  2. (2 points) Figure out how to change the radius of the tube cross section.
+
+  3. (5 points) Locate the famous transcendental constant π in the code.
+
+### FOOTNOTES
+
+[1] You can call such a transformation an "ambient isotopy" if you want to
+impress people at parties.
+
+[2] Also known as the "unknot", which sounds slightly less impressive than
+"ambient isotopy".
+
+[3] Unfortunately (for the author), the convenient excuse that LZW compression
+was not implemented in order to avoid the Unisys patent can no longer be used.
+
+[4] ;)