Fibonacci number

[jugaaru]

How to generate fibonacci mubers in C ?

[Leor Zolman]

On 22 Feb 2004 07:59:08 -0800, ju*****@yahoo.c om (jugaaru) wrote:

How to generate fibonacci mubers in C ?

At least two ways: iteratively (create an array, and populate it
on-the-fly), or recursively (have a function return 0 and 1 for the first
two Fibonacci numbers, and then have it calculate any other by calling
itself to acquire the previous two. Note that there's a /serious/
performance degradation for the 2nd technique, but it is more fun to code
;-)
-leor
Leor Zolman
BD Software
le**@bdsoft.com
www.bdsoft.com -- On-Site Training in C/C++, Java, Perl & Unix
C++ users: Download BD Software's free STL Error Message
Decryptor at www.bdsoft.com/tools/stlfilt.html

[Julian V. Noble]

jugaaru wrote:

How to generate fibonacci mubers in C ?

The algorithm is

F(n+1) = F(n) + F(n-1) , F(0) = 0, F(1) = 1

You can do this recursively (very stupid and slow--see my article
"Recurses!" in Computing in Science and Engineering) or iteratively
(much better).

I won't tell you how to do it since it is evidently homework.

Julian V. Noble
Professor Emeritus of Physics
jv*@lessspamfor mother.virginia .edu
^^^^^^^^^^^^^^^ ^^^
http://galileo.phys.virginia.edu/~jvn/

"For there was never yet philosopher that could endure the
toothache patiently."

-- Wm. Shakespeare, Much Ado about Nothing. Act v. Sc. 1.

[Sean Kenwrick]

"jugaaru" <ju*****@yahoo. com> wrote in message
news:d7******** *************** ***@posting.goo gle.com...

How to generate fibonacci mubers in C ?

#include <stdio.h>

int main() {

printf("fibonac ci mubers in C\n");
return 0;
}

[osmium]

jugaaru wrote:

How to generate fibonacci mubers in C ?

http://en.wikipedia.org/wiki/Fibonacci_number

Save the root of that link, it is a nice one to have handy for all sorts of
questions.

[Papadopoulos Giannis]

jugaaru wrote:

How to generate fibonacci mubers in C ?

Since it is definately a hw, I do not think that anyone should give you
an answer - the only way to learn is to get your feet wet..

But consider the following:

1) In the recursive solution, the resulting code is really trivial and
small (hint: the smallest possible is 3 lines).. Perfomance is missing
though...

2) Prefer the iterative solution, although it may seem a bit more
complicated..
When I was given the exercise, I had also to optimize my code for many
calls to the fibonacci procedure..
I used a static array to hold already calculated fibonacci numbers, to
speed up execution...
That is, the first time you calculate the 10th number, the array was
filled with some of the previous numbers.. Now, if you have to calculate
the 20th number, you don't need to do it all over again... Calculating
the 5th number is tricky though ;)...

3) I think I said enough already...

--
#include <stdio.h>
#define p(s) printf(#s" endian")
int main(void){int v=1;*(char*)&v? p(Little):p(Big );return 0;}

Giannis Papadopoulos
http://dop.users.uth.gr/
University of Thessaly
Computer & Communications Engineering dept.

[Dik T. Winter]

In article <8i************ *************** *****@4ax.com> Leor Zolman <le**@bdsoft.co m> writes:

On 22 Feb 2004 07:59:08 -0800, ju*****@yahoo.c om (jugaaru) wrote:

How to generate fibonacci mubers in C ?

At least two ways: iteratively (create an array, and populate it
on-the-fly), or recursively (have a function return 0 and 1 for the first
two Fibonacci numbers, and then have it calculate any other by calling
itself to acquire the previous two.

I prefer the direct, third, method. But you must not forget to include
math.h in that case (for the pow function). Moreover, it will not be
accurate when you wish use 64-bit integers.
--
dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, [phone]
home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/

[jugaaru]

Papadopoulos Giannis <ip******@inf.u th.gr> wrote in message news:<c1******* ****@ulysses.no c.ntua.gr>...

jugaaru wrote:

How to generate fibonacci mubers in C ?

Since it is definately a hw, I do not think that anyone should give you
an answer - the only way to learn is to get your feet wet..

But consider the following:

1) In the recursive solution, the resulting code is really trivial and
small (hint: the smallest possible is 3 lines).. Perfomance is missing
though...

2) Prefer the iterative solution, although it may seem a bit more
complicated..
When I was given the exercise, I had also to optimize my code for many
calls to the fibonacci procedure..
I used a static array to hold already calculated fibonacci numbers, to
speed up execution...
That is, the first time you calculate the 10th number, the array was
filled with some of the previous numbers.. Now, if you have to calculate
the 20th number, you don't need to do it all over again... Calculating
the 5th number is tricky though ;)...

3) I think I said enough already...

--
#include <stdio.h>
#define p(s) printf(#s" endian")
int main(void){int v=1;*(char*)&v? p(Little):p(Big );return 0;}

Giannis Papadopoulos
http://dop.users.uth.gr/
University of Thessaly
Computer & Communications Engineering dept.

--------------------
Yeah you are right, this is a Homework. I have just started learning
C, I am having trouble learning it. First 2-3 chapters, i can
understand variables,equat ion, somethings like maths. But when the
faculty start giving assignment. You have no clue how to do it.
Please advise how do i learn C programming.

[osmium]

jugaaru writes:

Yeah you are right, this is a Homework. I have just started learning
C, I am having trouble learning it. First 2-3 chapters, i can
understand variables,equat ion, somethings like maths. But when the
faculty start giving assignment. You have no clue how to do it.
Please advise how do i learn C programming.

Using the link I provided can you write a function to return F(0)? F(1)?
F(2)? F(3)? Do this with pencil and paper. Now try the other way,
starting with F(3) and working down. Then generalize the method you
discover and write a program to automate the process.

Perhaps you will be more comfortable with this alternative assignment:
Write a program to print the first ten Fibonacci numbers. Do that first,
throw it away, and then do the assigned problem. That essentially divides
the problem into two simpler problems.

[CBFalconer]

"Julian V. Noble" wrote:

jugaaru wrote:

How to generate fibonacci mubers in C ?

The algorithm is

F(n+1) = F(n) + F(n-1) , F(0) = 0, F(1) = 1

You can do this recursively (very stupid and slow--see my article
"Recurses!" in Computing in Science and Engineering) or iteratively
(much better).

I won't tell you how to do it since it is evidently homework.

But I will for two reasons: 1. Enough time has passed so that the
homework should have been passed in. 2. If the OP can rework the
following into something the instructor will believe is his, he
will have learned something.

BTW the following shows up a glitch in DJGPP 2.03 system. Calling
the program with an argument of -1 returns the overflow condition,
because strtoul returns ULONG_MAX rather than 0. Cross-posted to
comp.os.msdos.d jgpp for this.

#include <stdio.h>
#include <stdlib.h>

/* ------------------ */

/* deliberately written to upset some style mavens */
/* returns ULONG_MAX for overflow */
static unsigned long fibo(unsigned int n)
{
unsigned long pprev, prev, value;

if ((pprev = 0) == n) value = pprev;
else if ((prev = 1) == n) value = prev;
else do {
value = pprev + prev; pprev = prev; prev = value;
if (value < pprev) {
value = -1; /* ULONG_MAX, overflow */
goto x;
}
} while (2 <= --n);
x: return value;
} /* fibo */

/* ------------------ */

int main(int argc, char **argv)
{
unsigned int n;

if (2 != argc) puts("Usage: fibo N");
else {
n = strtoul(argv[1], NULL, 10);
printf("fibonac ci(%u) = %lu\n", n, fibo(n));
}
return 0;
} /* main */

--
Chuck F (cb********@yah oo.com) (cb********@wor ldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net> USE worldnet address!