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#76 2012-01-23 11:01:32

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

hi JEF

no no.it's something we've done last year.

hi bobbym

well it would be nice. smile


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#77 2012-01-23 11:07:37

bobbym
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From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

HI;

Prove that n^3+20n -10 is not O(n^2).


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#78 2012-01-23 11:12:25

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

hi

so n^3+20n-10>c*n^2 for any finite real number c>0.so n^3+20n-10 is w(n^2) and W(n^2) if i'm not mistaken.

i think that's enough for today.just tell me if i got this one right.


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#79 2012-01-23 11:20:39

bobbym
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From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

I do not remember about little w and Big W. But you are correct in the question.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#80 2012-01-23 21:12:13

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

hi bobbym

next?


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#81 2012-01-24 01:16:48

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Describe the growth of


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#82 2012-01-24 11:47:03

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Hi anonimnystefy;

You have two questions for you to work on.

What does O(1) really mean? Put your answer in terms of a physical problem, something computer related.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#83 2012-01-24 21:33:35

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

hi bobbym

1.n/((n+1)/2) is O(1)

2.O(1) means that an application with this complexity means that for any input it will take the same time to execute.e.g. the finding of the first element in an array has complexity of (1).


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#84 2012-01-25 01:12:43

bobbym
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From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Correct!

What is the Big(O) of this loop structure;

int x
for(x = 1; x<n; x*=2)
  {
    cout<< "hello";
  }


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#85 2012-01-25 06:20:08

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Hi anonimnystefy;

What does O(2^n) mean in cumputerese? Would you recommend an algorithm that had this amount of complexity?


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#86 2012-01-25 08:04:30

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

hi bobbym

1.it's O(log n)
2.well it's time doubles when we add one more element.time grow very very quickly,so i would never recommend it.

unfortunately i cannot think of any algorithms that are O(2^n)


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#87 2012-01-25 08:07:36

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Hi;

Very good!

You probably have never seen an O(2^n) algorithm.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#88 2012-01-25 08:11:30

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

probably.you?

next?


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#89 2012-01-25 08:13:02

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

When we say O(log(n)), clarify.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#90 2012-01-25 08:25:56

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

it means that the algorithm execution time grow slower than a linear algorithm.for example if we have 1 element the execution time will be 1,if we have 2 then it's 2,but for 3 it's also 2,for 4 it would be 3,and so on.

example algorithm is binary search algorithm.


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#91 2012-01-25 08:26:45

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

True but there is one more oddity about it. Check the notation for a clue.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#92 2012-01-25 08:42:54

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

well i don't know what it is.maybe it's that the base needn't be specified.


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#93 2012-01-25 08:44:01

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Hmmm! You were close. In normal mathematics log(n) means logs to the base e. Here it is in base 2.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#94 2012-01-25 08:52:49

TheDude
Member
Registered: 2007-10-23
Posts: 361

Re: Oh,Oh,Oh,merry analysis!!!

Sorry to be pedantic, but when base isn't specified isn't log(n) usually base 10 and ln(n) base e?


Wrap it in bacon

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#95 2012-01-25 08:55:50

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

hi bobbym

i don't agree.somewhere log is used to represent base 10 and ln for base e.


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#96 2012-01-25 08:59:46

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Hi TheDude and anonimnystefy;

Yes, you are correct. I use ln rather than log, but Mathematica, (Wolfram ) uses the notation log(n) for the natural logarithm. I should have been clearer in making that distinction.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#97 2012-01-25 09:04:57

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

it's okay.you're just used to it.

next?


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#98 2012-01-25 09:07:38

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

Hold on, because I have answered this question before. If you look here

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

in notations near the top you will see that when no base is specified log(x) means the natural log ( base e ) and not the common one at least one branch of math too.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#99 2012-01-25 09:10:09

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,609

Re: Oh,Oh,Oh,merry analysis!!!

the writer uses it like that as well and probably doesn't know about the other notation.


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#100 2012-01-25 09:13:33

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,147

Re: Oh,Oh,Oh,merry analysis!!!

It appears that either way depending on writers and branches of math both are correct.

For the purposes of asymptotic analysis log(n) means to the base 2.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

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