What is "lambda"?

[Groami Geistalt]

Hi
I see the word "lambda" used but I never understand what it means. (Apart from it being the 11th letter in the Greek Alphabet.) What's its history in terms of video-anything? Is it a type of codec, does it reference some kind of algorithm, is it specific to video editing...? What does it mean, what does it do, why that word instead of some other word...?
Thanks

[newpball]

Could be anything but in computing it is related to functional programming where the boundaries between data and functions on this data are watered down.

[poisondeathray]

Where have you seen it?

In video and image processing it typically used in rate distortion optimization (RDO) models for compression. It's not necessarily specific to video world ("lambda" is use in many fields)

[Groami Geistalt]

Where have you seen it?

Most recently over at http://avisynth.org.ru/mvtools/mvtools2.html .

Is it just something people toss in as a space-holder, like 'foo' and 'bar'? X = this, lambda = that?

It feels like one of those things everyone else is talking about familiarly, 'knowledgeably' in class, and I'm wracking my brains trying to remember if the teacher's ever actually just introduced it and given it a clear, crisp, fundamental explanation.

[poisondeathray]

"lambda" doesn't necessarily have a specific meaning unless there is a specific context . It can be a variable that means something different in a different scenario

In the mvtools context, it tells you what it means in the documentation. This isn't something taught in school. It could have just as easily been called "mike" or "david"

You can visualize the effects of using different lambda values by using mshow() to see the motion vectors

[Groami Geistalt]

Thanks, that's what I'd been wondering. That school reference was just an analogy for the feeling of confusion: Where'd "lambda" come from, how did it come to be a word used in so many ways when it doesn't seem to have any meaningful origin of its own that would explain its presence in these contexts.
Cheers

[poisondeathray]

I don't know the origins, besides "Greek"

But it sure sounds "scientific-y"

You can see it's used in many diverse areas, that have absolutely no relationship to one another. So if there is some historical relevance, many fields don't use that in their choice of using "lambda"

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

[Groami Geistalt]

Yup. Another perfectly cromulent word!

I like how Python uses it. "May as well call it lambda, I'm just going to throw it away anyway..."

Thanks, all.

[poisondeathray]

maybe "lambda" sounds better than "lamb-baaa"

[Groami Geistalt]

Oh great, so it's used in connection with RAM as well...

[sambat]

Ewe said it!

[netmask56]

Way back when homosexuality was banned, a small medallion of the Greek letter lambda hanging on a golden chain around the neck was used to indicate one's orientation to others. So lambda has a very varied use......