# +/- ve notation for roots, positive/negative, etc.

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• May 9th 2011, 05:29 AM
Ackbeet
+/- ve notation for roots, positive/negative, etc.
So, help me out here: what does the notation -ve and +ve mean? I've seen it used with respect to Descartes's Rule of Signs, I think. It's usually used on polynomials, and I think it has something to do with whether a polynomial is positive or negative in a certain region. Or it might have something to do with the location of roots.

Is it an abbreviation? If so, for what?

Google and AcronymFinder didn't help at all on this one, because it's so short, and I'm wondering if it really is an acronym.

Thanks!
• May 9th 2011, 05:33 AM
TheChaz
Quote:

Originally Posted by Ackbeet
So, help me out here: what does the notation -ve and +ve mean? I've seen it used with respect to Descartes's Rule of Signs, I think. It's usually used on polynomials, and I think it has something to do with whether a polynomial is positive or negative in a certain region. Or it might have something to do with the location of roots.

Is it an abbreviation? If so, for what?

Google and AcronymFinder didn't help at all on this one, because it's so short, and I'm wondering if it really is an acronym.

Thanks!

positive and negative, respectively. I think it's obnoxious.
• May 9th 2011, 05:42 AM
Plato
Quote:

Originally Posted by Ackbeet
So, help me out here: what does the notation -ve and +ve mean? I've seen it used with respect to Descartes's Rule of Signs, I think. It's usually used on polynomials, and I think it has something to do with whether a polynomial is positive or negative in a certain region. Or it might have something to do with the location of roots.
Is it an abbreviation? If so, for what? Google and AcronymFinder didn't help at all on this one, because it's so short, and I'm wondering if it really is an acronym.

I have never used that notation myself.
But I think that the ve is shorthand for variation.
Descartes's Rule of Signs counts the number of changes(variations) in signs in both \$\displaystyle P(x)~\&~P(-x)\$ thus counting the possible number of positive and negative roots.
• May 9th 2011, 05:42 AM
Ackbeet
Quote:

Originally Posted by TheChaz
positive and negative, respectively. I think it's obnoxious.

Positive and negative what? Roots? Do the letters ve stand for anything?
• May 9th 2011, 05:46 AM
Ackbeet
Quote:

Originally Posted by Plato
I have never used that notation myself.
But I think that the ve is shorthand for variation.
Descartes's Rule of Signs counts the number of changes(variations) in signs in both \$\displaystyle P(x)~\&~P(-x)\$ thus counting the possible number of positive and negative roots.

So a +ve would represent a change from - to +, and a -ve would represent a change from + to -?
• May 9th 2011, 05:58 AM
TheChaz
Quote:

Originally Posted by Ackbeet
Positive and negative what? Roots? Do the letters ve stand for anything?

As far as I can tell, the letters "ve" simply come from the words:
positive and negative.
• May 9th 2011, 06:21 AM
Ackbeet
Quote:

Originally Posted by TheChaz
As far as I can tell, the letters "ve" simply come from the words:
positive and negative.

Wow. Yeah, I'd agree that that's a pretty obnoxious notation. Thanks!
• May 9th 2011, 06:28 AM
CaptainBlack
Quote:

Originally Posted by Ackbeet
So, help me out here: what does the notation -ve and +ve mean? I've seen it used with respect to Descartes's Rule of Signs, I think. It's usually used on polynomials, and I think it has something to do with whether a polynomial is positive or negative in a certain region. Or it might have something to do with the location of roots.

Is it an abbreviation? If so, for what?

Google and AcronymFinder didn't help at all on this one, because it's so short, and I'm wondering if it really is an acronym.

Thanks!

+ve -ve are (relatively) common abbreviations for positive and negative respectively. They are not connected to Descartes rule of signs in particular but may occur when discussing the existence of +ve real roots and -ve real roots (just like that).

CB
• May 9th 2011, 06:30 AM
Ackbeet
So '+' stands for "positi", and '-' stands for "negati", right? What an abuse of English!
• May 9th 2011, 06:42 AM
TheChaz
Just a quick curiosity...
how does a thread become "[SOLVED]" ? Is that a moderator/admin decision, and/or does the OP clcik something to initiate the process???
• May 9th 2011, 07:08 AM
Ackbeet
Quote:

Originally Posted by TheChaz
Just a quick curiosity...
how does a thread become "[SOLVED]" ? Is that a moderator/admin decision, and/or does the OP clcik something to initiate the process???

The OP'er or a moderator can mark a thread as solved. At the top of any thread there's a drop-down listbox called Thread Tools. Everybody has some options in there (such as subscribe to the thread - which I use if I'm curious about a thread, but don't think I'm competant to answer the thread). If you are the OP'er or you moderate the forum for the thread you're viewing, you'll have an additional option in that menu labeled "Mark this thread as solved." And you can "unsolve it", too, if you've already marked it as solved.

Check it out here, which is the only thread you've started that you have permissions to view.
• May 9th 2011, 07:08 AM
Sambit
Quote:

Originally Posted by TheChaz
Just a quick curiosity...
how does a thread become "[SOLVED]" ? Is that a moderator/admin decision, and/or does the OP clcik something to initiate the process???

You see the Thread tools option just where the first post is made? Go there and click on the option Mark this thread as SOLVED, provided you are the one who started the thread. It has nothing to do with moderators or administrators.
• May 9th 2011, 07:12 AM
Ackbeet
Quote:

Originally Posted by Sambit
You see the Thread tools option just where the first post is made? Go there and click on the option Mark this thread as SOLVED, provided you are the one who started the thread. It has nothing to do with moderators or administrators.

See my post above.
• May 9th 2011, 07:16 AM
Sambit
Quote:

Originally Posted by Ackbeet
See my post above.

Saw it. Both you and me posted it in the same time. I had no intention to double-post the same thing. I saw it just after I posted mine.
• May 9th 2011, 07:17 AM
Ackbeet
Actually, I was referring more to the point that moderators and admins can mark any thread solved if it's in a forum they moderate. So moderating and administering does have something to do with it. Posting over someone else's post happens so often on this forum that it's really not worth getting worked up over.

Cheers.
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