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

You are not logged in.

- Topics: Active | Unanswered

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

Hi all,

I have this function's shape in mind...

plot y = |(x-5)|^[1-|(x-5)|] from x=0 to 5

Anyone seen this kind of curve before in a similar (i.e. simpler) function? I really had to "mess around" to make it lol!

math is fun! :-D

Prime numbers have got to be the neatest things; they are like atoms. Composites are two or more primes held together by multiplication.

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

Hi;

This is what I got:

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

Yes... so... I'm just wondering if you have seen this shape elsewhere in a simpler function (I'm not considering the rest, just this part of the plot as you got).

Prime numbers have got to be the neatest things; they are like atoms. Composites are two or more primes held together by multiplication.

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

The general shape looks like a skewed Standard Normal Curve. Sort of like the ones that are produced for Chi Square.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

That's true... do you have an equation in mind?

Prime numbers have got to be the neatest things; they are like atoms. Composites are two or more primes held together by multiplication.

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

Hi;

I might be able to fit one of those forms to that curve but why would that equation be better than the one we used to generate the curve?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

Very true. I guess if I represent it as

y = |x|^[1-|x|] from x=-5 to 0

It looks more simple and orderly

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

Hi;

You could simplify that a bit to

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

Whoa! That is good, bobbym. Thank you!

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

I only tested it from -5 to 0, so use with caution.

Mathematica believes that is true for x≤0. I would try to prove that first.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

What type(s) of function(s) would it be? I assume it is a power function and an exponential function.

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

Hi pellerinb;

I am not following you.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

Would it be a power function because it is y = | x ^...|

...likewise, would it be an exponential function because it has a variable in the exponent? Just curious.

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

Hi;

You mean this expression?

You mean is it a function? Or would you like to approximate that with a something else?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,018

bobbym wrote:

Hi;

You could simplify that a bit to

That does not look correct.

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: 107,736

It is a simplification of his answer in post #7. They are algebraically the same but not numerically!

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,018

They are not algebraically the same either!

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: 107,736

Have you plotted both?

Also

```
FullSimplify[Abs[x]^(1 - Abs[x]) == Abs[x^(1 + x)], {x <= 0}]
True
```

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

bobbym wrote:

Hi;

You mean this expression?

You mean is it a function? Or would you like to approximate that with a something else?

Yup, I mean, is it a function or what kind of function is it?

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,018

Yes, it is a function, but it does not have any particular name.

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

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

Thanks!

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,018

You are welcome.

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: 107,736

It does now have a name.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**pellerinb****Member**- Registered: 2012-12-26
- Posts: 43

It appreciates being addressed by unsaid name.

In biology, we use math like we know what we are talking about. Sad isn't it.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,736

The unsaid function is what it shall be called henceforth.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline