MsgBox(0,'',-27^(1/3)) [SOLVED]

[madflame991]

Try this:

MsgBox(0,'',-27^(1/3))

It should return -3...

Edited December 10, 2009 by madflame991

[water]

I'm not good at math (anymore) but isn't this the cube root of -27? And I think the root of a negative number isn't defined in AutoIt.

Edited December 10, 2009 by water

[99ojo]

Hi,

it should indeed. I don't know if it is really a bug, the dev's should decide.

MsgBox(0,'',-(27^(1/3)))

;-))

Stefan

[jvanegmond]

It shouldn't return -3.

[99ojo]

It shouldn't return -3.

Why?

Extraction Wikipedia:

The cube roots of a number x are the numbers y which satisfy the equation

Real numbers........

If x and y are real, then there is a unique solution and so the cube root of a real number is sometimes defined by this equation. If this definition is used, the cube root of a negative number is a negative number. The principal cube root of x is also represented by.......

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

Stefan

[jvanegmond]

I'm not talking about whether it should in mathematics, this is AutoIt. A programming language.

[99ojo]

So the answer is:

AutoIT doesn't return -3, because it isn't implemented to return cube roots of negative numbers.

MS calc.exe also doesn't.

;-))

Stefan

Your answer is misunderstandable.

[NerdFencer]

Manadar is thinking of the square root of a negative number such as

(-9)^(1/2)

to which the answer would be 3i if including answers outside the real domain

Without including answers in the imaginary plane, there is no result, and it is undefined

AutoIt does not support mathematics in the non-real plane and therefore it cannot find the even root of a negative number, but should be able retrieve the odd root of a negative number assuming that it supports all basic arithmetic in the real plane.

For

(-27)^(1/3)

You are taking the CUBE root of a negative number.

The answer is -3 because:

(-3)(-3)(-3) = -27

When multiplying the initial (-3)(-3) you get positive 9 because the negatives cancel

The third -3 reintroduces the negative, making the expression negative.

I personally would call the undefined result a bug, but one that is probably not worth fixing.

If you really want math outside the real domain, I suggest writing a UDF for it.

Edit: typo

Edited December 10, 2009 by NerdFencer

[madflame991]

I personally would call the undefined result a bug, but one that is probably not worth fixing.

If you really want math outside the real domain, I suggest writing a UDF for it.

I agree. It would eventually slow down the arithmetic evaluator.

[Mat]

http://www.autoitscript.com/forum/index.php?showtopic=98160

The question was exactly the example I gave.

Mat