subject:"\[R\] Fibonacci"

Re: [R] Fibonacci

2011-04-21 Thread Michael Dewey


At 10:42 20/04/2011, Georgina Imberger wrote:

Hi!

I am trying to work out the code to get a Fibonacci sequence, using the
while() loop and only one variable. And I can't figure it out.



 phi - 0.5 * (1 + sqrt(5))
 phi
[1] 1.618034
 fib - function(n) {(phi ^ n - (1 - phi) ^ n) / sqrt(5)}
 fib(1:10)
 [1]  1  1  2  3  5  8 13 21 34 55


Admittedly this does not use a while loop as you requested

Courtesy of Wikipedia



Fibonacci-c(1,1)
while (max(Fibonacci)500){
Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci)))
}


How can I tell R to take the value one before the max value? (Without
defining another variable)

(Probably super easy... I am a beginner...)

Thanks,
Georgie

[[alternative HTML version deleted]]


Michael Dewey
i...@aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html

__
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Re: [R] Fibonacci

2011-04-21 Thread David Winsemius



On Apr 21, 2011, at 9:04 AM, Michael Dewey wrote:


At 10:42 20/04/2011, Georgina Imberger wrote:

Hi!

I am trying to work out the code to get a Fibonacci sequence, using  
the

while() loop and only one variable. And I can't figure it out.



 phi - 0.5 * (1 + sqrt(5))
 phi
[1] 1.618034
 fib - function(n) {(phi ^ n - (1 - phi) ^ n) / sqrt(5)}
 fib(1:10)
[1]  1  1  2  3  5  8 13 21 34 55


Admittedly this does not use a while loop as you requested


I like it!

 test -c(  1,  1,  2,  3,  5,  8, 13, 21, 34, 55)
 test == fib(1:10)
 [1]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

To avoid such FAQ-tual puzzlement, it might be better to round to zero  
digits:


fib2 - function(n) {round( (phi ^ n - (1 - phi) ^ n) / sqrt(5) ) }

 test == fib2(1:10)
 [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE


There are several packages that offer fib() functions of one name or  
another, including the gmp package which always seems to think  
bigger than I do. I cannot (trivially) see how that author does it  
with fibnum(), because it is in a .Call()


--
David


Courtesy of Wikipedia



Fibonacci-c(1,1)
while (max(Fibonacci)500){
Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci)))
}


How can I tell R to take the value one before the max value? (Without
defining another variable)

(Probably super easy... I am a beginner...)

Thanks,
Georgie

   [[alternative HTML version deleted]]


Michael Dewey
i...@aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.


David Winsemius, MD
West Hartford, CT

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and provide commented, minimal, self-contained, reproducible code.

Re: [R] Fibonacci

2011-04-21 Thread Nordlund, Dan (DSHS/RDA)

 -Original Message-
 From: r-help-boun...@r-project.org [mailto:r-help-bounces@r-
 project.org] On Behalf Of David Winsemius
 Sent: Thursday, April 21, 2011 8:44 AM
 To: Michael Dewey
 Cc: r-help@r-project.org
 Subject: Re: [R] Fibonacci

 On Apr 21, 2011, at 9:04 AM, Michael Dewey wrote:

  At 10:42 20/04/2011, Georgina Imberger wrote:
  Hi!

  I am trying to work out the code to get a Fibonacci sequence, using
  the
  while() loop and only one variable. And I can't figure it out.

   phi - 0.5 * (1 + sqrt(5))
   phi
  [1] 1.618034
   fib - function(n) {(phi ^ n - (1 - phi) ^ n) / sqrt(5)}
   fib(1:10)
  [1]  1  1  2  3  5  8 13 21 34 55

  Admittedly this does not use a while loop as you requested

 I like it!

   test -c(  1,  1,  2,  3,  5,  8, 13, 21, 34, 55)
   test == fib(1:10)
   [1]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

 To avoid such FAQ-tual puzzlement, it might be better to round to zero
 digits:

 fib2 - function(n) {round( (phi ^ n - (1 - phi) ^ n) / sqrt(5) ) }

   test == fib2(1:10)
   [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE

 There are several packages that offer fib() functions of one name or
 another, including the gmp package which always seems to think
 bigger than I do. I cannot (trivially) see how that author does it
 with fibnum(), because it is in a .Call()

 --
 David

  Courtesy of Wikipedia

  Fibonacci-c(1,1)
  while (max(Fibonacci)500){
  Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci)))
  }

  How can I tell R to take the value one before the max value?
 (Without
  defining another variable)

  (Probably super easy... I am a beginner...)

  Thanks,
  Georgie

 [[alternative HTML version deleted]]

  Michael Dewey
  i...@aghmed.fsnet.co.uk
  http://www.aghmed.fsnet.co.uk/home.html

I, too, like the Michael/David/Wikipedia solution.  But if this is homework, I 
would recommend using length() instead of max() for getting the last two items 
of the vector.

Hope this is helpful,

Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA 98504-5204

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Re: [R] Fibonacci

2011-04-21 Thread William Dunlap

 -Original Message-
 From: r-help-boun...@r-project.org 
 [mailto:r-help-boun...@r-project.org] On Behalf Of Nordlund, 
 Dan (DSHS/RDA)
 Sent: Thursday, April 21, 2011 9:19 AM
 To: r-help@r-project.org
 Subject: Re: [R] Fibonacci

  -Original Message-
  From: r-help-boun...@r-project.org [mailto:r-help-bounces@r-
  project.org] On Behalf Of David Winsemius
  Sent: Thursday, April 21, 2011 8:44 AM
  To: Michael Dewey
  Cc: r-help@r-project.org
  Subject: Re: [R] Fibonacci

  On Apr 21, 2011, at 9:04 AM, Michael Dewey wrote:

   At 10:42 20/04/2011, Georgina Imberger wrote:
   Hi!

   I am trying to work out the code to get a Fibonacci 
 sequence, using
   the
   while() loop and only one variable. And I can't figure it out.

phi - 0.5 * (1 + sqrt(5))
phi
   [1] 1.618034
fib - function(n) {(phi ^ n - (1 - phi) ^ n) / sqrt(5)}
fib(1:10)
   [1]  1  1  2  3  5  8 13 21 34 55

   Admittedly this does not use a while loop as you requested

  I like it!

test -c(  1,  1,  2,  3,  5,  8, 13, 21, 34, 55)
test == fib(1:10)
[1]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

  To avoid such FAQ-tual puzzlement, it might be better to 
 round to zero
  digits:

  fib2 - function(n) {round( (phi ^ n - (1 - phi) ^ n) / sqrt(5) ) }

test == fib2(1:10)
[1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE

If you are going to round anyway, you can save time and
add puzzlement by leaving out the (1-phi)^n term:

   fib3 - function(n) {round( (phi ^ n) / sqrt(5) ) }
   all(fib2(0:100) == fib3(0:100))
  [1] TRUE

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

  There are several packages that offer fib() functions of one name or
  another, including the gmp package which always seems to think
  bigger than I do. I cannot (trivially) see how that author does it
  with fibnum(), because it is in a .Call()

  --
  David

   Courtesy of Wikipedia

   Fibonacci-c(1,1)
   while (max(Fibonacci)500){
   Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci)))
   }

   How can I tell R to take the value one before the max value?
  (Without
   defining another variable)

   (Probably super easy... I am a beginner...)

   Thanks,
   Georgie

  [[alternative HTML version deleted]]

   Michael Dewey
   i...@aghmed.fsnet.co.uk
   http://www.aghmed.fsnet.co.uk/home.html

 I, too, like the Michael/David/Wikipedia solution.  But if 
 this is homework, I would recommend using length() instead of 
 max() for getting the last two items of the vector.

 Hope this is helpful,

 Dan

 Daniel J. Nordlund
 Washington State Department of Social and Health Services
 Planning, Performance, and Accountability
 Research and Data Analysis Division
 Olympia, WA 98504-5204

 __
 R-help@r-project.org mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide 
 http://www.R-project.org/posting-guide.html
 and provide commented, minimal, self-contained, reproducible code.

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

[R] Fibonacci

2011-04-20 Thread Georgina Imberger

Hi!

I am trying to work out the code to get a Fibonacci sequence, using the
while() loop and only one variable. And I can't figure it out.

Fibonacci-c(1,1)
while (max(Fibonacci)500){
Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci)))
}


How can I tell R to take the value one before the max value? (Without
defining another variable)

(Probably super easy... I am a beginner...)

Thanks,
Georgie

[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Re: [R] Fibonacci

2011-04-20 Thread Erich Neuwirth

The easy solution to compute the Fibonacci numbers is
 
fibo - function(n,a=1,b=1){
 if (n == 1) return(a)
 if (n == 2) return(b)
 return(fibo(n-1,b,a+b)) 
}

It avoids double recursion.
It is, however, not as resource efficient as a loop since R does not do
tail recursion elimination.




On Apr 20, 2011, at 11:42 AM, Georgina Imberger wrote:

 Hi!
 
 I am trying to work out the code to get a Fibonacci sequence, using the
 while() loop and only one variable. And I can't figure it out.
 
 Fibonacci-c(1,1)
 while (max(Fibonacci)500){
 Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci)))
 }
 
 
 How can I tell R to take the value one before the max value? (Without
 defining another variable)
 
 (Probably super easy... I am a beginner...)
 
 Thanks,
 Georgie
 
   [[alternative HTML version deleted]]
 
 __
 R-help@r-project.org mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
 and provide commented, minimal, self-contained, reproducible code.
 

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R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Re: [R] Fibonacci

2011-04-20 Thread Petr Savicky

On Wed, Apr 20, 2011 at 11:42:38AM +0200, Georgina Imberger wrote:
 Hi!
 
 I am trying to work out the code to get a Fibonacci sequence, using the
 while() loop and only one variable. And I can't figure it out.
 
 Fibonacci-c(1,1)
 while (max(Fibonacci)500){
 Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci)))
 }
 
 
 How can I tell R to take the value one before the max value? (Without
 defining another variable)

Is it allowed to use length() function? If so, then try
the following

  Fibonacci-c(1,1)
  while (max(Fibonacci)500){
  Fibonacci-c(Fibonacci, Fibonacci[length(Fibonacci) - 1] + 
Fibonacci[length(Fibonacci)])
  }

Petr Savicky.

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Re: [R] Fibonacci

2011-04-20 Thread Nutter, Benjamin

Fibonacci - c(1, 1)
while (max (Fibonacci)  500){
  Fibonacci - c(Fibonacci, sum(tail(Fibonacci, 2))) } 

-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
On Behalf Of Georgina Imberger
Sent: Wednesday, April 20, 2011 5:43 AM
To: r-help@r-project.org
Subject: [R] Fibonacci

Hi!

I am trying to work out the code to get a Fibonacci sequence, using the
while() loop and only one variable. And I can't figure it out.

Fibonacci-c(1,1)
while (max(Fibonacci)500){
Fibonacci-c(Fibonacci, (max(Fibonacci) + ?(Fibanacci))) }

How can I tell R to take the value one before the max value? (Without
defining another variable)

(Probably super easy... I am a beginner...)

Thanks,
Georgie

[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

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Re: [R] Fibonacci

2011-04-20 Thread Bart Joosen

Another solution:

while (Fibonacci[1]  500)  Fibonacci - c(sum(Fibonacci[c(1,2)]),
Fibonacci)

While this adds the sum before the existing values, the length or tail
function or avoided, but even with reordering, its faster
(Fibonacci[length(Fibonacci):1])

Best regards

Bart


--
View this message in context: 
http://r.789695.n4.nabble.com/Fibonacci-tp3462636p3463050.html
Sent from the R help mailing list archive at Nabble.com.

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[R] Fibonacci

2011-04-20 Thread Georgina Imberger

Thank-you all!!
Very helpful.

-- Forwarded message --
From: Bart Joosen bartjoo...@hotmail.com
Date: 20 April 2011 15:46
Subject: Re: [R] Fibonacci
To: r-help@r-project.org

Another solution:

while (Fibonacci[1]  500)  Fibonacci - c(sum(Fibonacci[c(1,2)]),
Fibonacci)

While this adds the sum before the existing values, the length or tail
function or avoided, but even with reordering, its faster
(Fibonacci[length(Fibonacci):1])

Best regards

Bart

--
View this message in context:
http://r.789695.n4.nabble.com/Fibonacci-tp3462636p3463050.html
Sent from the R help mailing list archive at Nabble.com.

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[[alternative HTML version deleted]]

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