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#1 2012-11-23 14:47:13

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
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Newton Fractal

Will anyone expain me the basic principle behind the generation of Newton Fractals?

I think I have a basic( and only a very basic) idea of The Newton-Raphson Method, Calculus and Complex Number

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#2 2012-11-23 17:17:00

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

Hi;

What expression are they iterating through Newton Raphson?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#3 2012-11-23 18:11:31

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
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Re: Newton Fractal

They? Who are they?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#4 2012-11-23 18:18:34

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

Good question. Is there some function being iterated?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#5 2012-11-23 18:24:00

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
Website

Re: Newton Fractal

Actually, this is not something I am being taught at school.
I am just trying to learn it and know about its basics

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#6 2012-11-23 18:30:33

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

Hi;

newton's generates lots of fractals. here is one;

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#7 2012-11-23 18:33:53

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
Website

Re: Newton Fractal

No! What's the name of the book?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#8 2012-11-23 18:36:50

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

"Chaos Making a New Science" by James Gleick

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#9 2012-11-23 19:36:37

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
Website

Re: Newton Fractal

What is the basic principle behind generation of fractals?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#10 2012-11-23 19:39:46

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

The instability of Newton's iteration is the main thing!

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#11 2012-11-23 19:45:01

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
Website

Re: Newton Fractal

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#12 2012-11-23 19:50:22

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

We would have to go over it to really understand that. But I can say that everyone is taught to use it as model of efficiency. Oh, the way it zooms in on the roots of the canned problems that are given it in books.

Truth is unless you get a good initial guess, one that is close to the root in a special Newton's will go haywire.

In short it exhibits sensitivity to initial conditions, the mark of Chaos!

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#13 2012-11-23 21:08:04

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
Website

Re: Newton Fractal

Chaos is nice!

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#14 2012-11-23 21:08:59

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

Nope! Chaos is a big mess.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#15 2012-11-23 21:16:29

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,620
Website

Re: Newton Fractal

Why? Don't you enjoy randomness?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

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#16 2012-11-23 21:30:17

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

I am a numerical analyst. I consider that nothing but round off error, algorithm error. We try to eliminate it and Chaoticians are trying to show it, highlight it.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#17 2012-11-23 23:02:52

phrontister
Real Member
From: The Land of Tomorrow
Registered: 2009-07-12
Posts: 4,530

Re: Newton Fractal

Hi Bobby,

Truth is unless you get a good initial guess, one that is close to the root in a special Newton's will go haywire.

Yes, that's what happens with your towers problem if I use Newton's Method.

I wrote an LB program for it, and unless my initial guess is between 33.886745 and 39.999999, LB goes crosseyed.

``````    PROMPT "Enter approx. x (>33.886745 and <39.999999)";x\$
x=VAL(x\$)
[loop]
a=1/SQR(2500-x^2)+1/SQR(1600-x^2)-1/10
IF ABS(a-z)<0.000000001 THEN PRINT "15-digit approximation of x: ";USING("##.#############",x):END
z=a
b=x/(2500-x^2)^(3/2)+x/(1600-x^2)^(3/2)
x=x-a/b
GOTO [loop]

Output (for input between 33.886745 and 39.999999):
"15-digit approximation of x: 37.3550853341325"``````

Last edited by phrontister (2012-11-24 01:42:04)

"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

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#18 2012-11-23 23:06:24

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

Hi;

Newton's has that problem and a few others.

In the case of that program you might try improving it by replacing this line:

IF a=z THEN

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#19 2012-11-24 00:05:21

phrontister
Real Member
From: The Land of Tomorrow
Registered: 2009-07-12
Posts: 4,530

Re: Newton Fractal

Hi Bobby,

I don't understand why that line needs changing.

Would this be better?

IF a-z=0 THEN

"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

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#20 2012-11-24 00:16:17

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

Remember a while back with the loop that counted down from 1 to 0 by .1?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#21 2012-11-24 00:33:49

phrontister
Real Member
From: The Land of Tomorrow
Registered: 2009-07-12
Posts: 4,530

Re: Newton Fractal

Hmmmm......thinking........still thinking.........and.......nope!

I think you mentioned that case not all that long ago, and I think that I recalled it then. But not now! Grumble.

What was it again? (sorry)

"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

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#22 2012-11-24 00:40:38

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

The comparison of two floating point numbers for equality is always dangerous.

z = a is a possible problem

Take a look over here and see what I mean:

http://www.mathisfunforum.com/viewtopic … 56#p117156

post #18

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#23 2012-11-24 01:03:25

phrontister
Real Member
From: The Land of Tomorrow
Registered: 2009-07-12
Posts: 4,530

Re: Newton Fractal

Ah...yes. I remember that now. *slaps forehead*

When I wrote "IF a=z THEN" I thought that a & z would never actually equal each other (except with an integer solution, maybe?), but I went for that option anyway because I couldn't come up with anything better then, and it happened to halt program execution at the right time.

I still haven't thought of a way to overcome that, and I couldn't glean anything from that past discussion. I probably don't understand it well enough now, although I think I did at the time.

Any hints for this one?

"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

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#24 2012-11-24 01:05:08

phrontister
Real Member
From: The Land of Tomorrow
Registered: 2009-07-12
Posts: 4,530

Re: Newton Fractal

Maybe a FOR/NEXT loop?

"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

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#25 2012-11-24 01:29:09

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 108,524

Re: Newton Fractal

Hi;

How about the solution of not testing for equality but test whether they are close

Abs[a-z]<.0005

You can adjust the .0005, it is just for illustration,

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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