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# variation

Variation and proportion are defined to be the relationship between two or more variables with regard to a constant of proportionality.

The traditional notation for direct proportionality is $x\propto y$ or, if using regular equality notation, $x=ky$.

Here, $k$ denotes the constant of proportionality.

Similarly, the traditional notation for inverse proportionality is $x\propto 1/y$ or, with regular equality, $x=k/y$.

For direct proportionality, to find the value of an unknown $x$ or $y$, you may use the formula: $y_{{1}}/x_{{1}}=y_{{2}}/x_{{2}}$

Similarly, for inverse proportion it would be: $x_{{1}}/y_{{1}}=y_{{2}}/x_{{2}}$

Defines:

Relationships between two or more variables.

Related:

HomogeneousEquation, GraphOfEquationXyConstant, ProportionalityOfNumbers

Synonym:

Proportion

Type of Math Object:

Topic

Major Section:

Reference

## Mathematics Subject Classification

08C99*no label found*

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## Comments

## Search machine

The search machine of PM (i.e. Google) does not find all searched words, e.e. "inverse machine" although there is such PM entry and two references to this. What is the cause?

## Re: Search machine

I mean of course "inverse number" (I'm perhaps a little tired=o)

## Re: Search machine

Probably because the site was down for a few days recently, and Google started removing PlanetMath pages from its index when it realised they were no longer there.

## Re: Search machine

wasn't "inverse number" added this very day?

I'd e surprised if google had already indexed within a few hours

my bet is that it was just too new

f

G -----> H G

p \ /_ ----- ~ f(G)

\ / f ker f

G/ker f

## Re: Search machine

drini wrote:

> wasn't "inverse number" added this very day?

Yes, it was. I didn't realise that when I wrote my reply. So you're right that it just hasn't been indexed yet.

But there are other articles missing from Google for the reason I gave (e.g., DihedralGroup).

## why internal search does't work? (Re: Search machine)

Using the opportunity, let me ask a question: when the internal search engine will work? I remember very dimly that it worked very long time ago, but since then it always directs to google. And why actually internal search doesn't work?

## Re: why internal search does't work? (Re: Search machine)

it works intermintently, I don't know the details, but it seems there's a big that makes it stop working after soem time and needs to be manually fixed up each time

f

G -----> H G

p \ /_ ----- ~ f(G)

\ / f ker f

G/ker f

## Re: why internal search does't work? (Re: Search machine)

I think I mentioned this some time ago, but maybe it would be best to just skip the screen that says it's temporarily out of order, and just automatically direct the search through Google?

Especially when the site is running really slowly, this would save some loading time (and thus, presumably, processing power), and also would get rid of the "broken" feel.

Cam