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Fibonacci and the original problem about rabbits where the series first appears,
the family trees of cows and bees, the golden ratio and the Fibonacci series,
the Fibonacci Spiral and sea shell shapes, branching plants,
flower petal and seeds, leaves and petal arrangements, on
pineapples and in apples, pine cones and leaf arrangements.
All involve the Fibonacci numbers - and here's how and why.
More on the Fibonacci series and related mathematics:
looks at the patterns in the Fibonacci numbers themselves,
the Fibonacci numbers in Pascal's Triangle.
There are many
investigations for you to do to find patterns for yourself.
Is there a direct formula to compute Fib(n) just from n?
Yes there is! This page shows what it is and why it
involves Phi and phi - the golden section numbers.
is also sometimes called the golden ratio or the golden mean or the
divine proportion and is often denoted by the greek letter phi
which is sometimes printed as
or by another greek letter tau
.
It is closely connected with the Fibonacci series and has a value of 1.61803... .
We call it Phi on these pages, give its value to 2000 decimal places.
It has some interesting properties.
Phi is (sqrt(5)+1)/2 and phi is (sqrt(5)-1)/2 .
Two pages are devoted to the marvellous geometrical facts about the
golden section number - first in flat (or two dimensional) geometry and then
the solid geometry of three dimensions.
See some of the
unexpected places that the golden section (Phi) occurs in Geometry and in Trigonometry:
pentagons and decagons,
paper folding
and Penrose Tilings.
The trigonometry section looks at the
graphs of the sine, cosine and tangent functions and Phinds Phi Phrequently!
The golden section occurs in the most symmetrical of all the
three-dimensional globe-like solids - the Platonic solids.
What are the best shapes for fair dice? Why are there only 5?
All the powers of Phi are just whole multiples of itself
plus another whole integer (and guess what these whole integers are?
Of course - the Fibonacci numbers again!)
Here you can see some of the
amazing numerical properties of Phi and the Fibonacci numbers.
Introduction to Continued Fractions page takes these ideas further.
See Fibonacci numbers in brick wall patterns,
Fibonacci bee lines, seating people in a row and the Fibonacci numbers
again,
giving change and a game with match sticks and even
with electrical resistance and lots more puzzles
all involve the Fibonacci numbers!
It's all on this page!
If you know the Fibonacci Jigsaw puzzle where rearranging the pieces makes a
additional square appear,
did you know the same puzzle can be rearranged to make a
another shape where a square now disappears?
There is another way to look at Fibonacci's Rabbits problem that gives an infinitely
long sequence of 1s and 0s, which we will call the Fibonacci Rabbit sequence:-
1 0 1 1 0 1 0 1 1 0 1 1 0 ...
which is a close relative of
the number the golden section and the Fibonacci numbers.
You can hear the Golden sequence as a Quicktime movie track too!
The Fibonacci Rabbit sequence is an example of a fractal.
The number Phi occurs has been used to design many buildings
from the ancient Parthenon in Athens (400BC) to Le Corbusier's
United Nations building in New York.
It was well known by artists such as Leonardo da Vinci
and musicians too from composers like Bartok to the famous violin
maker Stradivari.
You know we use base 10 for written numbers, and computers use base 2,
but what about
using the Fibonacci numbers as the column headers? or base Phi (1.618034...) instead
of base 10?
is an advanced page if you have mastered
all the above. It shows that there is an interesting way of representing all
integers in a binary-like fashion but using only powers of Phi instead of
powers of 2 (binary) or 10 (decimal).
There are several ways to compute pi (3.14159 26535 ..) accurately.
One that has been used a lot
is based on a nice formula for calculating which angle has a given tangent, discovered
by James Gregory. His formula together with the
Fibonacci numbers can be used to compute pi.
This page introduces you to all these concepts from scratch.
Sometimes we find series that for quite a few terms look exactly like the
Fibonacci numbers, but, when we look a bit more closely, they aren't - they are
Fibonacci Forgeries.
Since we would not be telling the truth if we said they were the
Fibonacci numbers, perhaps we should call them Fibonacci Fibs
!!
Here is a series that is very similar to the Fibonacci series,
the Lucas series, but it starts with 2 and 1 instead
of Fibonacci's 0 and 1. It sometimes pops up in the pages above so here
we investigate it some more - or rather, there are lots of interesting and simple
investigations for you to do to discover its properties for yourself!
New results added to the Things To Do section (March 98).
There are many links on the pages above as well as references to some excellent books
and articles.
This page contains links to other sites on Fibonacci numbers and the
Golden section
so there is
more yet for you to explore.
I am preparting a list of Fibonacci and Phi Formulae.
An incomplete draft version (March 98)
is available as a 1.6Mb postscript file (.ps) which is gnu-zipped
(.gz) down to 802Kb. This will be expanding shortly as more fomulae are added.
Other citations:
This site was an Exploratorium
Top 10 Cool site for August 1997.
It is included in the new Dorling Kindersley web site
the Active Learning Club Guide on the Internet for
children aged 7-11, designed to take
children to high-quality web sites that cover topics included in the
Children's Encyclopedia.
It was recommended in "Computers Update" section of the
Times Education Supplement of 14 March 1997.
A talk at your school/college/organisation?
Would you like a talk at your school, college or other organisation
on the Fibonacci Numbers and the Golden Section?
I have given such talks at the Orkney Science Festival (the second largest
Science Festival in the UK in a wonderful part of the world - the Orkney Islands
just off the north coast of Scotland) and also at many schools and colleges.
Click on the "Dr Ron Knott" link at the foot of the page for
contact details.
This page has been accessed
times since March 1996.
Currently there are around 200 visitors per day to this page.
The counter passed 80,000 in May 1998, so if it is around zero then our
Web server disk has become full again
which seems to clear this counter to zero!
It'll be restored fairly soon!