Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

**genericname****Member**- Registered: 2012-05-16
- Posts: 52

(2*(n/2)*lg(n/2)) + n

= (n*lg(n/2))+n

= n*(lg n - 1) + n

How does **(n*lg(n/2))+n** simplify to **n*(lg n - 1) + n**? What happened to the n/2 that was inside? It has been a while since I last worked with log.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,171

Hi;

Is this the problem?

*Last edited by bobbym (2013-02-25 08:51:47)*

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

Offline

**genericname****Member**- Registered: 2012-05-16
- Posts: 52

Yeah.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,171

I am getting:

*Last edited by bobbym (2013-02-25 10:10:52)*

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,015

Hi genericname

lg(a/b)=lg(a)-lg(b) for any a and b for which the expression is defined.

So, lg(n/2)=lg(n)-lg(2)=lg(n)-1, assuming the logarithm is with base 2.

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

The knowledge of some things as a function of age is a delta function.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,171

Why would the log be to the base two?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,015

Because then the step makes sense. We will have have to wait for the OP's answer.

And besides, the use of n and lg reminds me of comp. analysis.

*Last edited by anonimnystefy (2013-02-25 14:42:40)*

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

The knowledge of some things as a function of age is a delta function.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,171

A very good answer!

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**genericname****Member**- Registered: 2012-05-16
- Posts: 52

Ah, thank you. It was base 2, sorry for the confusion.

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,015

No problem and you're welcome!

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

The knowledge of some things as a function of age is a delta function.

Offline

Pages: **1**