Neither positive nor negative ?

[phya]

See any reasonably comprehensive dictionary.


This term is precisely defined in mathematics, and the definition has been given numerous times in this thread. Why are you still asking a question that has already been answered?

For a real number x,
|x| = \left\{ \begin{array}{l l}x & \text{if x } > 0\\ 0 & \text{if x } = 0 \\ -x & \text{if x }< 0 \end{array} \right.

Note that +x and x mean the same thing.

Because this answer is wrong, it has been stepped asked.
Please answer here on the Absolute it.

 

[phya]

Again, if I may, I think the crux here lies in the fact that phya is seeing that absolute values are magnitudes should thus be unsigned, (since a sign such as + or - indicates a direction.

i.e. magnitude is the unsigned scalar property of a vector.

So, question: does it make sense to have a scalar with a sign, or is it simply an unsigned value?

Only the magnitudes of unsigned indeed exist.

 

[JaredJames]

Only the magnitudes of unsigned indeed exist.

Hate to be so blunt but you don't seem to accept the facts, this thread resembles the majority of perpetual energy discussions.

If it doesn't have a sign, it is positive (except 0). Period.

There is nothing to debate. You are confusing two different things (vectors and scalars).

 

[Mark44]

This term is precisely defined in mathematics, and the definition has been given numerous times in this thread. Why are you still asking a question that has already been answered?

For a real number x,
|x| = \left\{ \begin{array}{l l}x & \text{if x } > 0\\ 0 & \text{if x } = 0 \\ -x & \text{if x }< 0 \end{array} \right.

Note that +x and x mean the same thing.

Because this answer is wrong, it has been stepped asked.
Please answer here on the Absolute it.

This is not an answer; it's a definition. There's no point in discussing this with you if you are going to assert that a definition is wrong.

 

[JaredJames]

This thread has officially become the perpetual energy of maths. I say lock it.

 

[phya]

DaveC is correct, one of phyas problems is confusing scalars with vectors.

As an example, think of it as velocity vs speed:
north = +
south = -

+10mph = 10mph north
-10mph = 10mph south

What phya is doing is removing the direction sign (+/-) and simply looking at what is left, the 10mph. Which is a meaningless magnitude without an assigned direction.

In his case he has the direction which is either positive or negative and then the 'how much' (10, 20, 30 etc). This is where he is confusing things. He is removing the (+/-) and assuming the number left is meaningless, which is incorrect as many have pointed out, a number without a sign is simply positive (or neutral as the case with 0).

|speed|=velocity

|+10|=10
|-10|=10
|10|=10

 

[Char. Limit]

|speed|=velocity

|+10|=10
|-10|=10
|10|=10

Huh?

|\vec{v}|=s

The absolute value of speed is not velocity. The absolute value of velocity is speed.

 

[jgens]

|+10|=10
|-10|=10
|10|=10

Right, and each value that you posted above is positive. That's what the absolute value does; that's how it's defined.

Since you seem to be convinced that there are unsigned real numbers (other than zero), do you mind constructing such a system?

 

[JaredJames]

|speed|=velocity

|+10|=10
|-10|=10
|10|=10

No, |velocity|= speed.

If you read my example, this is exactly what I showed. By removing the sign you end up with a meaningless scalar magnitude when talking about velocity.

Note that all the speed magnitudes of 10 are positive.

This is NOT the same as your number example. Taking the absolute values makes them all positive (with the exception of zero). They are not scalars so you cannot compare them to that scenario.

 

[Mentallic]

Phya here's a thought, get over this topic, and learn some real maths.

 

[phya]

right, and each value that you posted above is positive. That's what the absolute value does; that's how it's defined.

Since you seem to be convinced that there are unsigned real numbers (other than zero), do you mind constructing such a system?

|+10|=|-10|=|10|=10
+10≠-10
-10≠10
+10≠10

 

[Mentallic]

+10≠-10
-10≠10
+10≠10

This is nonsense.

If a\neq b and b \neq c this doesn't imply a\neq c

This is all you said...

10\neq -10
-10\neq 10
10\neq 10

Phya quit being stubborn and just accept what you've been told. You won't get anywhere if you keep thinking that +10 is different to the number 10. Especially since you aren't showing us exactly how +10 and 10 differ by pointing out their separate spots on a number line. Of course, if you did this, I'm sure your version of the number line would be something more elaborate than usual.

 

[JaredJames]

phya

|+10|=|-10|=|10|=10=+10

Correct: +10≠-10
This is the same as above: -10≠10
Incorrect: +10≠10

I was always taught that the easy way of taking the absolute value of a number is to make it positive. Because that is what taking the absolute value does. There is no argument here, you are just talking a load of rubbish which cannot be substantiated.

 

[phya]

Again, if I may, I think the crux here lies in the fact that phya is seeing that absolute values are magnitudes should thus be unsigned, (since a sign such as + or - indicates a direction.

i.e. magnitude is the unsigned scalar property of a vector.

So, question: does it make sense to have a scalar with a sign, or is it simply an unsigned value?

The absolute value of a number is an unsigned number.

 

[JaredJames]

The absolute value of a number is an unsigned number.

The absolute value is positive. PERIOD.

Why are you arguing this?

You cannot compare vectors and scalars to this situation. It is not the same. My previous example shows you this but you don't seem to want to accept it.

Here is quote from the real numbers section of the wiki article (http://en.wikipedia.org/wiki/Magnitude_%28mathematics%29):

"The absolute value may be thought of as the number's distance from zero on the real number line. For example, the modulus of -7 is 7 and the modulus of −5 is 5."

Do you understand now? It is a positive value, showing how far a number is from zero on a number line.

 

[phya]

This is not an answer; it's a definition. There's no point in discussing this with you if you are going to assert that a definition is wrong.

This definition is unreasonable.

 

[Mark44]

This is not an answer; it's a definition. There's no point in discussing this with you if you are going to assert that a definition is wrong.

This definition is unreasonable.

Then you are in disagreement with every mathematician in the world.

The absolute value of a number is an unsigned number.

If by this you mean neither positive nor negative, then your understanding of this elementary mathematical function is deeply flawed.

 

[Mentallic]

This definition is unreasonable.

And then how is it more reasonable to have 10\neq +10 ?

 

[Mentallic]

I think this whole dispute stems from this quote:

Absolute value of a number we have three answers to choose from, be negative, be positive, be neither positive nor negative. Why do we choose a positive number it? This is not injustice it?

Honestly, I've never seen anyone that felt like maths was discriminating against... well... numbers.

 

[HallsofIvy]

The absolute value of a number is an unsigned number.

"unsigned number" is not a standard mathematics phrase. I have seen "unsigned int" in computer languages but that nothing to do with what is being discussed here. Please define "unsigned number".

 

[Mark44]

"unsigned number" is not a standard mathematics phrase. I have seen "unsigned int" in computer languages but that nothing to do with what is being discussed here.

Right. C and C-based programming languages have a number of unsigned data types, including unsigned int (AKA unsigned), unsigned char, unsigned short, and unsigned long. All values of these types, with the notable exception of 0, are positive.

 

[Mark44]

Congrats phya. We are up to post #82 and have not yet convinced you that the absolute value of a real number is zero or positive. This might be a record.

 

[Mentallic]

I can only think of two possible reasons.

Maybe we are bad explainers! No... wait... scratch that.

 

[phya]

Assuming the positive charge of electricity was 10, recorded as +10, the negative charge of electricity is 15, recorded as -15, then the power is how much? 10. Clearly, the 10 non-working non-negative.

 

[JaredJames]

Seriously, someone please lock this thread soon. This is no more than speculation and crack-pottery on phyas part. He can't even explain what an 'unsigned number' is.

I'm all for explaining to someone, but after 84 posts he still doesn't accept the laws of mathematics?

This thread isn't worth the database it's stored in. I can't believe the moderators are allowing this to continue. Perhaps locking would require I start explaining some new 'non-negative' thrust device for an aircraft using phyas logic?

 

[Hurkyl]

I wish someone would have reported this thread earlier; I hadn't noticed it.

It would certainly be more fruitful than the insults people are starting to border upon throwing around.