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Math Help - Subscript notation?

  1. #1
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    Subscript notation?

    Would someone be as kind to tell me what is meant in the following notation by the subscript 'thingies' that look exponents but are displayed below the number?

    I'm looking for a formal title so I can google up on the definition, thanks for your help. More generally, what are good resources for looking up idiosyncrasies in notation?

    Edit: Nevermind I just realized that the numerals are denoting the index / position in a vector / set. But where would I go in the future when notation confuses me?

    Edit 2: ok take this for instance: We can approximate this value by taking a point somewhere near to P(x, f(x)), say Q(x + h, f(x + h)).
    From: http://www.intmath.com/Differentiati...principles.php

    I don't understand the P(x, f(x)) part specifically, are they denoting probabilistic distribution, I don't think so, I've never seen a point defined like that when I've worked with Highschool level euclidean geometry informally, where do I even start to begin learning these counter-intuitive conventions
    Last edited by jshpro2; January 2nd 2009 at 02:42 AM.
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  2. #2
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    Quote Originally Posted by jshpro2 View Post
    Would someone be as kind to tell me what is meant in the following notation by the subscript 'thingies' that look exponents but are displayed below the number?

    I'm looking for a formal title so I can google up on the definition, thanks for your help. More generally, what are good resources for looking up idiosyncrasies in notation?

    Edit: Nevermind I just realized that the numerals are denoting the index / position in a vector / set. But where would I go in the future when notation confuses me?

    Edit 2: ok take this for instance: We can approximate this value by taking a point somewhere near to P(x, f(x)), say Q(x + h, f(x + h)).
    From: 3. The Derivative from First Principles

    I don't understand the P(x, f(x)) part specifically, are they denoting probabilistic distribution, I don't think so, I've never seen a point defined like that when I've worked with Highschool level euclidean geometry informally, where do I even start to begin learning these counter-intuitive conventions
    P and Q are points on the curve y = f(x). Ex. if y = x^2 then P and Q could be say P(1,1),\;\;Q(2,4)
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  3. #3
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    Quote Originally Posted by jshpro2 View Post
    Would someone be as kind to tell me what is meant in the following notation by the subscript 'thingies' that look exponents but are displayed below the number?

    I'm looking for a formal title so I can google up on the definition, thanks for your help. More generally, what are good resources for looking up idiosyncrasies in notation?

    Edit: Nevermind I just realized that the numerals are denoting the index / position in a vector / set. But where would I go in the future when notation confuses me?

    Edit 2: ok take this for instance: We can approximate this value by taking a point somewhere near to P(x, f(x)), say Q(x + h, f(x + h)).
    From: 3. The Derivative from First Principles

    I don't understand the P(x, f(x)) part specifically, are they denoting probabilistic distribution, I don't think so, I've never seen a point defined like that when I've worked with Highschool level euclidean geometry informally, where do I even start to begin learning these counter-intuitive conventions
    The experience of working with them for a while will make them intuitive eventually. You pick these up as you go along in math. You probably did not find algebra very intuitive at first - before learning algebra, you only manipulated numbers and then you suddenly stumbled among this thing called x, which is known. Right? But now you can deal with it, so you will be able to yet again.

    The P( ) is simply denoting a point. That point is (x,y)=(x,f(x)).

    If you do not understand something, look at several sources. I am sure that because the concept of a derivative is important, there will be many sites that can provide explanations for how it works. You are bound to understand at least one of those explanations.
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  4. #4
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    I am understanding it slowly, thanks for the reply. I figured out it meant the "return value" ( ala programming languages ) of the f(x) applied to that numeral in the Cartesian coordinate. I just wanted to make sure I wasn't missing some huge commonly accepted reference. I also saw a table of symbols used in the notation ( on wikipedia ) but it didn't really tell me "syntax" or conventions. I am learning though, I got some Knuth's on the way, what else is good?
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