HDTenEightyP/NetNews huggingface dataset:
From: israel@unixg.ubc.ca (Robert B. Israel)
Newsgroups: sci.fractals
Subject: Re: "Critical Points" for non-analytic functions
Date: 22 Nov 92 09:35:33 GMT
Organization: The University of British Columbia
NNTP-Posting-Host: unixg.ubc.ca

In <1992Nov21.154035.5381@mnemosyne.cs.du.edu> lmitchel@nyx.cs.du.edu (lloyd mitchell) writes:

>In sci.math, a question was asked about taking the derivative of a non-
>analytic complex function.  In particular, the poster was trying to 
>differentiate

>	f(z) = y + ix, where z = x + iy.

>My question is this:  For such functions, is there any such point that
>corresponds to a critical point for analytic functions?  I'm curious
>because I'd like to generate Mandelbrot-type sets for some functions of
>this nature, and I wonder where one would begin iterating.  (For analytic
>functions, Mandelbrot images are generated by beginning the iteration
>at a critical point.)

>Thanks for any info,
>Kerry Mitchell

You can always regard the complex plane as R^2, so you have a mapping from
R^2 to R^2.  The derivative in this context is the Jacobian matrix, and a
"critical point" would be one where the Jacobian has determinant 0.  These
would tend to occur on curves, however, not isolated points.  The dynamics
of arbitrary differentiable maps from R^2 to itself might be quite 
complicated compared to analytic functions, and I don't think there's an
awful lot that can be said about it in general.  In particular, there may be
no good reason to start iterating at any particular point.

-- 
Robert Israel                            israel@math.ubc.ca
Department of Mathematics             or israel@unixg.ubc.ca
University of British Columbia
Vancouver, BC, Canada V6T 1Y4
Newsgroups: sci.fractals
From: mhall@occs.cs.oberlin.edu (Matthew Hall)
Subject: Fractals in other Geometries?
Organization: Oberlin College Computer Science
Date: Fri, 20 Nov 1992 22:55:01 GMT
Distribution: sci.fractals
X-Posted-From: occs.cs.oberlin.edu
NNTP-Posting-Host: sol.ctr.columbia.edu

Hello
	I have to give a presentation about fractals for my
non-Euclidean geometry class.  Rather than just recite pretty much
what I already know about IFS's created with dilations, rotations, and
translations, I thought it would be much more interesting if I studied
IFS's in a geometry other than Euclidean.  
	Plane hyperbolic geometry looks very promising, since it has
the addition of another type of transform.  However, I haven't found
any references to this.  Eventually, I would like to prove the theorem
that says the random algorithm is equivalent to the deterministic
algorithm in non-euclidean geometries.  If anyone has any help to give
me, or any sources of information, I would be very grateful.

Thanks,
-matt hall
--
-------------------------------------------------------------------------------
Matt Hall.    mhall@occs.oberlin.edu  OR  SMH9666@OBERLIN.BITNET
              (216)-775-6613 (That's a Cleveland Area code. Lucky Me)

                         F(X)=M*X*(1-X)  

Newsgroups: sci.fractals
From: omitchel@jarthur.claremont.edu (Ocie Mitchell)
Subject: Re: Help with making the PLASMA image in C
Keywords: How to calculate the colours ?
Organization: Harvey Mudd College, Claremont, CA 91711
Date: Thu, 19 Nov 1992 19:34:21 GMT

In article <DNORT.1.722078665@gribb.hsr.no> DNORT@gribb.hsr.no (Johansen, Trond Robert 6-96) writes:
>I am new in fractals, but I am trying to learn about it by making my own 
>pictures. I am making a recursive function that is suppost to draw the 
>plasma picture. The functions get a rectangle and divides this rectangel 
>into four "simmular" rectangels inside the first, and so on. My problem now 
>is how to calculate the colours. I know that the colours (of the four 
>corners) depends uppon a random value, and the "mother" rectangle, but HOW 
>does it depend? I also know that when the rectangle is big (at the start of 
>recursion), then the colour depends more of the random than of the colours 
>of the "mother" rectangle.
>
[code deleted]
>I dont know if this is the kind of questions that peopel ask here, but 
>anyway I will be greatfull for all the help I gets.
>
>Trond Robert Johansen
>DNORT@GRIBB.HSR.NO  (Internett)

I think what you want to do is pick 4 random colors for the corners and then
color the midpoints of the rectangle with a color that is the average of the
colors at its endpoints +/- a random factor that has a magnitude proportional
to the length of the rectangle's side.  so if you started with the colors
(R,G,B)--------(r,g,b) you would insert a color 
           ^here
and its value would be ((R+r)/2+z*d,(G+g)/2+z*d,(B+b)/2+z*d)
where d is the distance from the first to second pixel and z is a random #
in the range -v<z<v.  By drawing pictures with different values of v you can
get smooth (v~0) or rough (v~2) pictures.  
Let me know how this works out, I don't have the resources to program for
255 color graphics (or even 3 colors)
Ocie

----------------------------------------------+-------------------------------
``What do you think sirs?''  -Joel (mst3k)    | .sig lite- all .sig no guilt
----------------------------------------------+------------------------------- 
   __             _ _ _                       | Ocie Mitchell
  / ')           ' ) ) )  _/_    /      /) /) | omitchel@jarthur.claremont.edu
 /  / _. o _      / / / o /  _. /_  _  // //  | Q:is that your real name? 
(__/ (__(_(<_    / ' (_(_(__(__/ /_(<_(/_(/_  | A:yes, it is my real name.
----------------------------------------------+-------------------------------
From: ST202013@brownvm.brown.edu (dan goldwater)
Newsgroups: sci.fractals
Subject: Re: Fractint and Ray Tracers
Date: Sun, 15 Nov 1992 23:51:19 EST
Organization: Brown University - Providence, Rhode Island  USA
NNTP-Posting-Host: brownvm.brown.edu
News-Software: BNN via BNN_POST v1.0 beta

maybe the raytracing options could be put in their own sub-menu so most
people wouldnt have to deal with them, but the people that want to do
tracing can still have them.  i dont see any reason to just kill the code...
the people that do tracing usually dont mind recompiling fractint to fiddlewith
things.  and this is a lot easier than making custom scripts to make the
RAW triagle output useable...
maybe something useful would be a raw hightfield output type?  for the
tracers that cant read gif's for hightfields? (but i guess just using
piclab is also a possibility).  obviously specific hightfield output for
each raytracer would be nice, but that takes coding :) (which ones cant
input gifs for a hightfield besides rayshade?  rayshade is of course my
favorite..).
-dan goldwater-
daniel_goldwater@brown.edu      dgold@math.umass.edu
Xref: sparky sci.fractals:354 news.answers:4052
From: P.S.Mcdowell@lut.ac.uk (PS Mcdowell)
Newsgroups: sci.fractals
Subject: Speech recognition using fractal dimensions
Date: 16 Nov 92 16:03:53 GMT
Reply-To: P.S.Mcdowell@lut.ac.uk (PS Mcdowell)
Organization: Loughborough University, UK.

Can anybody help me with a literature survey I am carrying out as part of a 
Ph.D concerned with speech recognition using fractal dimensions.  So far I 
have only discovered one related paper on the subject, that by C. Pickover and
A. Khorasani (Computers & Graphics VOL 10 1986), and would therefore be
extremely grateful for any other related information on the subject 
(names, groups etc).

Thanks in advance,

Paul McDowell (LUT) 
Newsgroups: sci.fractals
From: mbk@lyapunov.ucsd.edu (Matt Kennel)
Newsgroups: sci.fractals
Subject: Re: Lorenz' Weather
Date: 16 Nov 1992 05:30:50 GMT
Organization: Institute For Nonlinear Science, UCSD
NNTP-Posting-Host: lyapunov.ucsd.edu
X-Newsreader: Tin 1.1 PL3

mroussel@alchemy.chem.utoronto.ca (Marc Roussel) writes:
: >	dX/dt = a(Y-X)
: >	dY/dt = bX-Y-XZ
: >	dZ/dt = XY - cZ
: >
: >				where a = 10
: >				      c = 8/3
: >				      b = control parameter (try 28)
: 
:      These are indeed the Lorenz equations (as they are now known) but
: these aren't the original weather simulation equations where Lorenz
: noticed sensitive dependence on initial conditions.  Lorenz actually
: started out with some specialized version of the Navier-Stokes equation
: (a PDE) and noticed sensitive dependence in these equations under the conditions
: of his weather simulation.  The Lorenz ODEs shown above are a truncation
: of the Navier-Stokes equation for the special case of (I think)
: Rayleigh-Benard convection under certain fairly restrictive conditions.

There is a physical system for which the Lorenz equations are a
"not incredibly bad" approximation (to use them for simple R-B convection is a 
"well that's really pretty cheezy" approximation).

It's called a thermosyphon, and it actually gets used for some engineering
applications but I don't know how really.

Think of a loop of pipe in an 'O' standing up vertically, like a bicycle
wheel, with fluid in the interior.

Now, keep the walls on the bottom half of the "O" hot, and the
walls on the top half cold. Given enough of a temperature difference,
you can start to get convective motion of the fluid as it tries to
transport heat from hot to cold.

In this circumstance, the "X" variable is proportional to fluid
velocity (in some complicated nondimensionalization), the Y and Z
variables are coefficients sine and cosine modes of the temperature.

"a" is the Prandtl number of the fluid (ratio of shear viscosity to
thermal diffusivity), "b" is the Rayleigh number (proportional to
temperature difference between hot and cold boundary conditions and
other geometrical factors), and "c" is always one.

: Lorenz cooked up these equations as a simple example of what he was
: seeing in his more sophisticated weather models.


: 				Marc R. Roussel
:                                 mroussel@alchemy.chem.utoronto.ca

--
-Matt Kennel  		mbk@inls1.ucsd.edu
-Institute for Nonlinear Science, University of California, San Diego
-*** AD: Archive for nonlinear dynamics papers & programs: FTP to
-***     lyapunov.ucsd.edu, username "anonymous".
From: noring@netcom.com (Jon Noring)
Newsgroups: sci.fractals
Subject: Mandelbrot Animation (FLI) Uploaded to Wuarchive
Date: 22 Nov 92 17:54:39 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest)

Hello,

I just uploaded to wuarchive.wustl.edu, in subdirectory /pub/MSDOS_UPLOADS,
a compressed (.zip) file containing manz2to4.fli.  The name of the file is
manz2to4.zip.

The file manz2to4.fli is a FLI animation file generated from Fractint 17.2
GIF files.  I generated 201 GIF files of resolution 320x200x256 using the
manzpower fractal type by varying the exponent (real part) from 2.00 to 4.00
in steps of 0.01.  I then used the program DTA15E to create the "movie".
Of course, when the exponent is 2.00, we get the familiar Mandelbrot
fractal that we know and love.

The uncompressed .fli file is large, about 1.2Meg.  Fortunately, it does
compress well, down to 540K.

This is my first attempt at animation of fractals.  My next attempts will
be to improve the resolution (to 640x480x256) and to improve the color
mapping.  In addition, I may explore the other Mandelbrot parameters as
well as other fractal types.  I may also generate "zoom movies".

If you don't have a FLI viewer, there are some available (for DOS) via
anonymous ftp from site wuarchive.wustl.edu in subdirectory
/mirrors/msdos/graphics.

If enough people request it, and it's been shown to work for most, I may
consider posting it to the alt.binaries.pictures.fractals newsgroup.  But
let's see if it works o.k. before I take that leap.  Please let me know
if you get it to work alright.

Jon Noring


-- 
=============================================================================
| Jon Noring          | noring@netcom.com        | "The dogs bark, but the  |
| JKN International   | IP    : 192.100.81.100   |  caravan moves on."      |
| 1312 Carlton Place  | Phone : (510) 294-8153   | "Pack your lunch, sit in |
| Livermore, CA 94550 | V-Mail: (510) 862-1101   |  the bushes, and watch." |
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the average coal miner did in 1949, adjusted for taxes and inflation," John
Sestina, nationally recognized Certified Financial Planner;  quoted in 1987.

------->   I VOTED FOR PEROT IN '92
------->   support UNITED WE STAND!
From: mitch@lakes.trenton.sc.us (mitch quinn)
Newsgroups: sci.fractals
Subject: NEW
Date: Wed, 18 Nov 92 00:34:02 EST
Reply-To: mitch@lakes.trenton.sc.us (mitch quinn)
Organization: Lakes Public Access

Hello, guys, I'm new to the group, FRACTINT v 15 got me started. and I 
was wondering where I can find the latest version. 

Thanks in Advance.              
                                Mitch Quinn
             /s
Xref: sparky sci.fractals:353 comp.theory.dynamic-sys:353 sci.systems:145 comp.theory.self-org-sys:126
From: mlevin@husc8.harvard.edu (Michael Levin)
Newsgroups: sci.fractals,comp.theory.dynamic-sys,sci.systems,comp.theory.self-org-sys
Subject: anyone know the algorithms for Pokorny and/or Glynn fractals
Date: 19 Nov 92 03:54:33 GMT
Article-I.D.: husc3.1992Nov18.225434.17589
Distribution: world
Organization: Harvard University Science Center


     I just saw some images created by algorithms called Pokorny and
Glynn fractals (in Clifford Pickover's new book - sincerely
reccommended, by the way). Does anyone know the pseudocode for these
algorithms? I wasn't able to recreate them from what was said in the
book. If anyone has any ideas, references, etc., please email to
mlevin@husc8.harvard.edu. 
btw, I don't have access to any math literature search database... :(

Mike Levin
Newsgroups: sci.fractals
From: twegner@mwunix.mitre.org (Timothy Wegner)
Subject: Christmas Chaos
Summary: Request for "Christmas Chaos" code hints
Keywords: symmetry scientific american lorenz fractals
Organization: The MITRE Corporation
Date: Thu, 19 Nov 1992 14:15:48 GMT

The latest Scientific American has some great fractals in a section called
"Christmas Chaos". They are "Lorenz" type orbit fractals, and they look
incredibly easy to code. I tried the three-way-symmetry formula and got it
"working" in a few minutes (added it to Fractint using the "lorenz" engine)
but it didn't give any decent image at all. If anyone has any hints please
email me. Probably some simple thing I overlooked, but the fractal formulas
are so straight-forward it is hard to see where I went wrong. Only thing I
can think of is that the viewing region in the complex plane was not given,
and I was using something like an origin-centered box roughly 16 on a side.

--
Tim Wegner     Fractint co-author
Internet: twegner@mwunix.mitre.org  Compuserve: 71320.675@compuserve.com
Newsgroups: sci.fractals
From: james@panix.com (James Britt)
Subject: fractal foam
Date: Thu, 19 Nov 1992 14:51:07 GMT
Organization: PANIX Public Access Unix & Internet, NYC

The November 14 issue of Science News has a cover article about
"fractal foam", derived from an itteritive function that has three
attractors.  Has anybody else seen this?  The article is not very
explanitive on just where the attractors lie.  I've tried to
code this, but the results don't look anything like the pictures.
If anyone has more info on this, please let me know.

Thank you!

James Britt
-- 
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Just another speed-metal vegetarian anarchist cyberhippie Zen Socratic...
Diblo Rules!                                        Hack The Wetware!
james@panix.com  .............................................................
From: bert.tyler@satalink.com (Bert Tyler)
Newsgroups: sci.fractals
Subject: Data-dependent bug in Fra
Date: 20 Nov 92 17:55:00 GMT
Reply-To: bert.tyler@satalink.com (Bert Tyler)
Organization: Datamax/Satalink Connection * Ivyland, PA (215) 443-9434

Jon Noring / Barry Smith reported problems while running Fractint and
the image generated by the command-line options:

  type=complexnewton corners=-6/5/5/-4 params=12/2/12/2 maxiter=2500
  periodicity=0

First the good news:  I just generated that fractal with no problems
using the current internal developer's test version of Fractint on
my 486/50DX2.  Took 21 minutes, 39 seconds for a 1024x768x256 image.

The big difference (both in terms of speed and in terms of
eventual success) was the fact that my PC had a math coprocessor
onboard and the other PCs didn't.  The newton algorithms involve
power functions, and the parameters used by this particular
complexnewton involve a *lot* of powers, and this really stresses
our internal math routines on FPU-less PCs.  In this case, it stressed
them until they broke.

My guess as to why one fellow got a visible error message while the other
got a trashed screen is that the second fellow's system threw his
PC partially (but not completely) out of its graphics video state
when it attempted to display that internal error message, and 
Fractint's graphics<->text video logic couldn't handle what was left.

                   Bert Tyler   (bert.tyler@satalink.com)
---
 . DeLuxe./386 1.25 #343sa . Void where prohibited.  Batteries not included.
                                                                                                           
Newsgroups: sci.fractals
From: helgeu@dhhalden.no (Helge Rene Uholm)
Subject: Re: Introductory talk
Organization: Ostfold College
Date: Thu, 19 Nov 1992 12:01:31 GMT

spedpr@thor.cf.ac.uk (Paul Richards) writes:

>Also, I am looking at ways of using fractals with neural networks. Are
>there any papers relating to this. Any combaination of the two in
>whatever way would be of interest at the moment.

>Please reply by mail.

	Send me the info too.

In advance thanks.	

helgeu@dhhalden.no
Newsgroups: sci.fractals
From: DNORT@gribb.hsr.no (Johansen, Trond Robert 6-96)
Subject: Help with making the PLASMA image in C
Keywords: How to calculate the colours ?
Organization: Rogaland University Centre
Date: Wed, 18 Nov 1992 09:24:25 GMT

I am new in fractals, but I am trying to learn about it by making my own 
pictures. I am making a recursive function that is suppost to draw the 
plasma picture. The functions get a rectangle and divides this rectangel 
into four "simmular" rectangels inside the first, and so on. My problem now 
is how to calculate the colours. I know that the colours (of the four 
corners) depends uppon a random value, and the "mother" rectangle, but HOW 
does it depend? I also know that when the rectangle is big (at the start of 
recursion), then the colour depends more of the random than of the colours 
of the "mother" rectangle.

The function that I have made is short and easy, and I'll explain what the 
variables is here:

(x1,y1) Upper left corner of the rectangle
(x2,y2) Lower rigt corner of the rectangle
fov   Colour to upper left corner
foh   Colour to upper right corner
fnv   Colour to lower left corner
fnh   Colour to lower right corner

Her is the function :

void plasma(int x1,int y1,int x2,int y2,
	    int fov,int foh,int fnv,int fnh)

{	
	/*?????? Calculate the colours (fov,foh,fnv and fng) ?????????*/

	if (y2>y1+1)	
	{  plasma(x1,y1,((x1+x2)>>1),((y1+y2)>>1),fov,foh,fnv,fnh);	
	   plasma(((x1+x2)>>1),y1,x2,((y1+y2)>>1),fov,foh,fnv,fnh);	   
	   plasma(((x1+x2)>>1),((y1+y2)>>1),x2,y2,fov,foh,fnv,fnh);	   
	   plasma(x1,((y1+y2)>>1),((x1+x2)>>1),y2,fov,foh,fnv,fnh);	
	}   	
	else	
	{  putpixel(x1,y1,fov);		
	   putpixel(x2,y1,foh);		
	   putpixel(x1,y2,fnv);
           putpixel(x2,y2,fnh);
	}


I dont know if this is the kind of questions that peopel ask here, but 
anyway I will be greatfull for all the help I gets.

Trond Robert Johansen
DNORT@GRIBB.HSR.NO  (Internett)
Newsgroups: sci.fractals
Subject: what are the names of these fractal algorithms?
From: mlevin@husc8.harvard.edu (Michael Levin)
Date: 21 Nov 92 18:11:27 EST
Distribution: usa
Organization: Harvard University Science Center


    Suppose you do a regular Julia set algorithm - for each point in
the screen x,y you make z = x+yi and then iterate z = f(z) for some
complex function f(). Now, what are the names of each of the following
ways of determining the color of the initial (x,y)?
1. color = number of iterations to reach a certain |z|
2. color = |z_final| (distance of the final z from the origin, after a
   certain number of iterations)
3. color = |z_final - z_original| (how far the point ended up from
   where it started)

  What are these called? Please reply to mlevin@husc8.harvard.edu.

Mike Levin
Newsgroups: sci.fractals
From: sbw1@ra.msstate.edu (Scott Brian Wright)
Subject: Printing Fractals...
Organization: Mississippi State University
Date: Fri, 20 Nov 1992 19:18:54 GMT

Hello,
I have a paper to turn in Monday, and I'd like to include a few b&w printouts
of my fractal designs. I have access to a lazer printer and am curious as to
how i would go about printing out my .gif files. Would i have to copy the 
entire Fractint software onto the computer hooked up to the laser printer?

Any suggestions would be greatly appreciated! I hope you can help me before
Monday. Thanks in advance.

Scott B. Wright - sbw1@ra.msstate.edu - Mississippi State University, Starkville
From: bert.tyler@satalink.com (Bert Tyler) 
Newsgroups: sci.fractals
Subject: Saving
Date: 19 Nov 92 17:25:00 GMT
Distribution: world
Organization: Datamax/Satalink Connection * Ivyland, PA (215) 443-9434
Reply-To: bert.tyler@satalink.com (Bert Tyler) 

JG>        I have been trying to save a gif after I generate it using a
JG>'ram video' resolution in the background of Fractint 17.2 (one of the
JG>higher resolutions which my screen cannot show). When I try to save the
JG>file I get an error message saying that the file cannot be saved.

John, can you be a bit more specific?  I've looked all over the
Fractint source code, and can't find any error messages that 
say anything like "Fractint cannot save the file...".  I've
found "Can't open...", "Can't Write...", and "Disk Full..." error
messages, but not that one.

I just generated some Disk/RAM video images and saved them without
any problems - right up until I filled up my hard disk to force
the "Disk Full" error message.

I'm afraid that we need more info before we can help you here.

                   Bert Tyler   (bert.tyler@satalink.com)
---
 . DeLuxe./386 1.25 #343sa . Did you expect mere proof to sway my opinion?
                                                                                         
Newsgroups: sci.fractals
From: mccasal@nyx.cs.du.edu (Massimo Casal)
Subject: c*e^z
Organization: Nyx, Public Access Unix (sponsored by U. of Denver Math/CS dept.)
Disclaimer1: Nyx is a public access Unix system run by the University of
Disclaimer2: Denver for the Denver community.  The University has neither
Disclaimer3: control over nor responsibility for the opinions of users.
Date: Mon, 16 Nov 92 18:08:16 GMT

Hi!
so i did my prgram to create julia sets images of c*e^z
i used c real part > 50 to stop the iteration..
which is a good range to evaluate that julia sets?

Thanx
Massimo Casal

email:casal@udmi5400.cineca.it

Newsgroups: sci.fractals
From: awhitloc@ringer.cs.utsa.edu (Andrea G. Whitlock)
Subject: Re: c*e^z
Organization: University of Texas at San Antonio
Date: Wed, 18 Nov 1992 13:49:31 GMT

In article <1992Nov16.180816.3517@mnemosyne.cs.du.edu> mccasal@nyx.cs.du.edu (Massimo Casal) writes:
>Hi!
>so i did my prgram to create julia sets images of c*e^z
>i used c real part > 50 to stop the iteration..
>which is a good range to evaluate that julia sets?
>

From -3 to 3 works pretty well.

-- 
Andrea G. Whitlock @ The University of Texas at San Antonio, Division of MCSS
awhitloc@ringer.cs.utsa.edu	|	In the force if Yoda's so strong,
whitlock@lonestar.utsa.edu	|	construct a sentence with words in
1mcagw@utsa86.utsa.edu		|	the proper order then why can't he?