Talk:Proportionality (mathematics)

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If y = kx + c, then would it not be correct to say that y is proportional to x, or y is directly proportional to x irrespective whether or not c = 0 or non-zero?

I'm pretty sure it is. I was just about to comment on that issue.

I don't think so. Their change is proportional, but they are not themselves.--Patrick 12:44, 23 August 2005 (UTC)
No, they're not proportional unless c = 0. 198.59.188.232 02:44, 24 October 2005 (UTC)

Contents

[edit] Direct proportionality

There is no distinction made between merely proportional and directly proportional, in the article. Perhaps one could be made by commenting on the origin graphically.00:36, 1 November 2005 (UTC)

[edit] what is the symbol for inverse?

the article shows that the symbol for directly proportional is α (alpha), but it doesn't say what the symbol for inverse proportional is. can anyone share that with me, i am having trouble remmebering it. I think its either a backwards alpha or an alpha with a line over or under it, something like that. can anyone help?--68.249.39.158 18:18, 14 February 2006 (UTC)

I thought it was just written as "x is proportional to the reciprocal of y", like this: X α 1/Y capitalist 03:41, 15 February 2006 (UTC)
The sign of proportionality is not the greek lower case letter alpha (α), but the symbol ∝ (in Arial Unicode MS the symbol is a bit too small, in most type faces it is bigger, as seen in LaTeX: \propto). In some countries, Sweden for instance, the symbol \sim or ∼ is used instead of ∝. The Unicode-code for ∝ is U+221D (Proportional to) and for ∼ U+223C (Tilde operator). /85.197.143.234 21:51, 27 May 2006 (UTC)

[edit] Even more symbols

So there is no difference in ∝ and ∼? While checking the Mathematical Operators table at http://www.decodeunicode.org/w3.php?ucHex=2200 i found the character ∽ by the name reversed tilde - maybe this is the inverse proportional sign? By the way, there are many more abstruse characters found in this part of Unicode with most of them hardly to figure out. Maybe someone can help out and expand (that is create redirects) for these characters? Thanks, --Abdull 21:29, 28 May 2006 (UTC)

[edit] Graphs

Graphs would be helpful here, for examples of an inverse direct and an inverse square relationship. I don't have an SVG editor, so the only thing I can provide is a PNG... Titoxd(?!?) 07:43, 25 June 2006 (UTC)

[edit] Proportionality to x^2?

Should there be a section on proportionality of x^n (n=1,2,3....)? --124.217.57.41 13:19, 4 September 2007 (UTC)BY Mr. Ignacio

[edit] Improving article

Some suggestions for improving this article include having separate articles for direct and inverse proportion, as they are sufficiently comprehensive and practical topics that deserve separate articles (the redirects will have to be fixed. I must say that I am surprised this article and also ratio are quite short, given their usefulness in real life. I will try to expand the articles once I find the time. I encourage others to help ! Thanks. MP (talk•contribs) 19:20, 19 April 2008 (UTC)

Given the ubiquity of direct proportion in civilization's systems of rationality, one might expect that that cousin "inverse proportion" would get some attention too. But once you look for sources and experts, books and articles, and real instantiation, the subject slips away into obscurity. Presently I am madly attempting to provide references for the article hyperbolic coordinates which is linked from the paragraph that we have presently. Probably the best evidence for obscurity comes from special relativity, where the hyperbolic curve of inverse proportion is taken for a map of the potential future moment, depending on the speed (or rapidity). The decades it has taken experts to expose the underlying linear algebra of Lorentz' transformations reflects the delicacy of parsing a physical model. Please, yes, if you have some references to build an article, that would be of great assistance.Rgdboer (talk) 20:45, 19 April 2008 (UTC)