Author:
- Name: Leonid A. Broukhis
Location: US - United States of America (United States)
To build:
make allBugs and (Mis)features:
The current status of this entry is:
STATUS: known bug - please help us fix
For more detailed information see 1995/leo in bugs.html.
To use:
./leo [ deep ] [ right ] [ Variable ] [ cycle [ freq ] ]See the author’s information below on these details.
Try:
./try.shJudges’ remarks:
Press return after each image is drawn.
The variable names are element-ary. If you find this confusing, remember that it is nu-clear. :-)
Some Ghostscripts/Postscript programs cleared the screen right after the image is drawn, so we added element 106 which acts as an input buffer.
To qualify for a category specially for yourself in the Geek code, find out all the secret switches that the author doesn’t divulge ! (All switches are single characters on the command line - anything that’s not a number is a candidate.)
Author’s remarks:
The usage is:
./leo [ deep ] [ right ] [ Variable ] [ cycle [ freq ] ]where the first three are literal words, cycle is a positive integer (0 is
ignored), and freq is an integer (default = 0) that’s supposed to be in the
range 0..100 (bigger values are allowed, however). Invalid parameters and
options usually stop the command line parsing (not always but why?). The actual
position of the word options does not matter, so ./leo right Variable 1 70 is
equivalent to ./leo 0 0 0 1 Variable 70 right, etc.
If Variable is used, cycle is almost ignored (see below) but has
to be present if you want to enter freq (and you usually do).
Some options to try (besides the obvious):
./leo 1 | cat - /dev/tty | gs -This draws the basic pattern I invented in high school:
You take a big sheet of “arithmetic” paper and draw a line of length 1 (between 2 crossings) at the center of the sheet:
|This makes 2 open ends (I think the notion of an “open end” doesn’t require explanations) in step 1. Now, until there are open ends in step N, repeat: for each open end pretend it points north and draw 2 lines going northwest and northeast from it to the nearest crossings. This needs to be done “simultaneously” for all ends that are open at that moment.
Step 2:
\./
|
/ \Step 3:
__| |__
\./
|
__ / \ __
| |
Step 4:
.
\./ \./
\__| |__/
/ \./ \
|
\__./ \.__/
/ | | \
/ \./ \Step 5:
._| . |_.
__| \./ \./ |__
\__| |__/
__./ \./ \.__
__I | I__
\__./ \.__/
__./ | | \.__
|_./ \./ \._|
| |
The lines marked by I show the places where “simultaneity” is significant.
Note that so far all the drawings represent valid structural formulas of some organic substances.
step 1: ethane step 2: 2,3-dimethylbutane step 3: (2,5-dimethyl;3,4-isopropyl)-hexane step 4 and 5: I don’t know. Do you?
Step 6:
\./ \./ \./ \./
._| . |_. ._| . |_.
\__| \./ \./ |__/ \__| \./ \./ |__/
/ \__| |__/ \ / \__| |__/ \
\__./ \./ \.__/ \__./ \./ \.__/
X__| | |__X or <__| | |__>
/ \__./ \.__/ \ / \__./ \.__/ \
\__./ | | \.__/ \__./ | | \.__/
/ |_./ \./ \._| / |_./ \./ \._|
| | | |
/ \ / \ / \ / \
depending on the desired “hairiness”. The original (paper-based) algorithm was “hairy”, but it didn’t look as good on the screen.
The program cannot handle non-hairy mode 100% correctly - step 6 happens to be
|__
...__/ ...__/
... \ ... \.
...__/ ...__/|__
...__Y and step 7: ...__Y
... \ ... \
...__/ ...__/
\ \.__
|
and so on: the horizontal symmetry has been lost. That’s why the opening for step 1 is not a single line but a cross:
\./
/ \To watch it repeatedly (as a screen saver), use:
./leo 2 | cat - /dev/tty | gs -The command line:
./leo Variable 1 | cat - /dev/tty | gs -draws the same as above. Try:
./leo Variable 1 1 | cat - /dev/tty | gs -What happened to the picture? Increase freq and watch the changes.
If cycle is more than 1, the program loops, allowing the user to
enjoy randomly changing patterns (the delay is 3 seconds),
but there is a secret switch to suppress looping: useful
if you want to pipe the output to a printer.
If Variable is used, the actual value of cycle doesn’t matter,
as far as it is > 1. To figure out what difference
cycle makes when Variable is not used, try
./leo Variable 37 80 | cat - /dev/tty | gs -and other values of cycle; smaller values usually require
smaller values of freq for the patterns to be non-trivial.
The options deep and right make the patterns to be drawn in different
manners. Try all the examples above with deep and with right.
What is the difference between them?
…There is a little flaw in the implementation of the algorithm, and sometimes the patterns are not symmetrical when they ought to be (the program needs to be slightly changed to expose the flaw, otherwise it is hardly noticeable, if ever).
A quick and dirty fix (turned on by another secret switch) makes the patterns symmetrical, but a little too HAIRY.
There is one more secret switch (it shall also remain nameless), and I don’t even want to explain what it does. You’ve been warned!
* * *Special thanks:
- to PostScript syntax designers for the curly braces;
- to Dmitry Mendeleyev for his periodic table of elements;
- to Hydrogen for having 2 more isotopes.
NOTICE to those who wish for a greater challenge:
If you want a greater challenge, don’t read any further: just try to understand the program via the source.
If you get stuck, come back and read below for additional hints and information.
Secret switch
See secret.html if you wish to know the secret switch.
Inventory for 1995/leo
Primary files
- leo.c - entry source code
- Makefile - entry Makefile
- leo.orig.c - original source code
- secret.html - web page with the secret switch
- try.sh - script to try entry
Secondary files
- 1995_leo.tar.bz2 - download entry tarball
- README.md - markdown source for this web page
- .entry.json - entry summary and manifest in JSON
- .gitignore - list of files that should not be committed under git
- .path - directory path from top level directory
- secret.md - markdown source for secret.html
- index.html - this web page
