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 2007-03-18, 20:26 #1 jasong     "Jason Goatcher" Mar 2005 3×7×167 Posts Need books about "crooked E" I contracted a mental illness when I was 16, so my education was pretty much cut short at that point. From the 11th to the 17th of April, I'll be going to and returning from my brother's wedding. 48 of those hours will be spent in a van. During that time, I'd like to increase my education by learning how to use the "crooked E" symbol. Apparently, I would've been learning about it a month or two after I became ill, because everything I've read is easy to understand up until that point. Could someone advise me on some question and answer books(I'd prefer that the questions and answers be in the same book, everything has to fit in a backpack.) that I could use to teach myself? Something I could buy on Amazon preferably. thanks in advance. :)
 2007-03-18, 21:53 #2 sdbardwick     Aug 2002 North San Diego County 2BF16 Posts Just for clarity, by "crooked E" did you mean this symbol?: $\Sigma$
2007-03-18, 22:05   #3
Wacky

Jun 2003
The Texas Hill Country

32×112 Posts

Quote:
 Originally Posted by sdbardwick Just for clarity, by "crooked E" did you mean this symbol?: $\Sigma$
It's "Greek" to me. :)

There are many characters (typically from the Greek alphabet) that have a particular meaning in mathematics. (The one that you reference is the uppercase form of "Sigma" which is generally used to indicate a summation.)

It is unclear to me whether Jason is interested in the symbolic notation or in some characteristics behind the relationships that they are used to represent.

He could also be referring to some form of "epsilon".

On Google, the only reference that I found to "Crooked E" was a reference to the Energy trading company, Enron. (Disclaimer: I have a "vulture" interest in some of the obligations of that company)

Last fiddled with by Wacky on 2007-03-18 at 22:07 Reason: Speeling

2007-03-19, 01:15   #4
Xyzzy

Aug 2002

20D816 Posts

Quote:
 He could also be referring to some form of "epsilon".
Epsilon, or epilepsy?

2007-03-19, 01:54   #5
jasong

"Jason Goatcher"
Mar 2005

3·7·167 Posts

Quote:
 Originally Posted by sdbardwick Just for clarity, by "crooked E" did you mean this symbol?: $\Sigma$
Just to clarify, yes, that is the symbol, and I'm interested in learning to do math with it.

 2007-03-19, 04:36 #6 paulunderwood     Sep 2002 Database er0rr 3×1,327 Posts $\Sigma$ means summation (in most contexts). Rather than writing something like: $1+a+a^2+a^3+a^4+a^5+a^6+a^7+a^8+a^9+a^{10}+a^{11}+a^{12}+a^{13}+a^{14}+a^{15}+a^{16}+a^{17}+a^{18}+a^{19}+a^{20}+a^{21}$ mathematicians express this as: $\Sigma_{i=0}^{i=21}a^i$ or sometimes something like this: $\Sigma_{i=0}^{21}a^i$ Assuming the distributive law: C*(A+B)==C*A+C*B and by repeatedly using it, you can see that: $C\times\Sigma_{i=0}^{i=21}a^i=\Sigma_{i=0}^{i=21}C\times a^i$ An interesting sum is: $\Sigma_{n=1}^{n=\infty}{\frac{1}{n^2}}$ (Hint: Euler's zeta function ) Things get hairy when you start nesting one $\Sigma$ inside another. Last fiddled with by paulunderwood on 2007-03-19 at 05:01
 2007-03-19, 04:49 #7 jasong     "Jason Goatcher" Mar 2005 1101101100112 Posts If it's so simple, maybe you could recommend a textbook to help me learn it? :)
2007-03-19, 10:30   #8

"Richard B. Woods"
Aug 2002
Wisconsin USA

22·3·641 Posts

Quote:
 Originally Posted by jasong During that time, I'd like to increase my education by learning how to use the "crooked E" symbol.
For future symbol references:

Switching your display font to some Unicode font (http://en.wikipedia.org/wiki/List_of...#Unicode_fonts) may help when viewing the following.

http://www.maths.tcd.ie/~dwilkins/La.../MathSymb.html

http://whatis.techtarget.com/definit...803019,00.html (warning: contains so many images they may not all load in IE until you clear cache)

http://en.wikipedia.org/wiki/Table_o...atical_symbols

Last fiddled with by cheesehead on 2007-03-19 at 10:33

 2007-03-19, 12:36 #9 m_f_h     Feb 2007 6608 Posts Indeed the "crooked E" is the greek letter Sigma (i.e. it's a crooked S and not an E...), for "Sum". I learned it with that one: Walter, Wolfgang: Analysis 1.. Springer-Lehrbuch. Berlin: Springer, 398 S. (2004). I liked his style: concise for the mathematics, very rich in historical comments. However, since it's in German, I don't know if it will help you. But I think any 1st year "analysis" (=calculus) book will deal with that, it's a question of personal preference which one you like better than another. Searching amazon.com for "calculus I" gives you the following as #1, I don't know it, but you can have a look inside the book ; searching for "infinite sum" takes you to p.203 where the "Sigma" is introduced. (It's over 300 pp but you can buy it used for \$13 - just the right thing for your travel...) http://www.amazon.com/Calculus-I-Und...4307268&sr=1-1 ("calculus I" by Mardsen,Mardsen & Weinstein, if the link does not work). Last fiddled with by m_f_h on 2007-03-19 at 12:37 Reason: but>buy
 2007-03-19, 14:13 #10 davieddy     "Lucan" Dec 2006 England 145128 Posts Jasong. If you know what a "loop" is in a computer program, that should help your understanding of this notation. David
 2007-03-19, 16:13 #11 philmoore     "Phil" Sep 2002 Tracktown, U.S.A. 111910 Posts Most textbooks on "College Algebra" or "Precalculus" also have introductory sections on sequences and series, including the sigma notation. This might be a good place to start, as these descriptions will not assume that the reader has any previous exposure to this material.

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