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qweretyq
Riemann Hypothesis
Riemann Hypothesis

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#1
euler's constant

i searched google for eulers constant and got approximately
0.577215665
But i always thought that euler's constant was
e? (lim x->infinity (1+1/x)^x)

can someone explain what euler's constant is?

PostPosted: Thu Mar 17, 2005 1:03 am
nr1337
Navier-Stokes Equations
Navier-Stokes Equations

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#2
There's two of them:

[URL=http://mathworld.wolfram.com/Euler-MascheroniConstant.html]The Euler-Mascheroni Constant :approx: 0.5772...[/URL]
e :approx: 2.718281828459045
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PostPosted: Thu Mar 17, 2005 1:11 am
Danbert
Riemann Hypothesis
Riemann Hypothesis


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#3
Euler has the distinction of being (maybe?) the only person with two constants named after him. The first, e , is
e=\lim_{x\to\infty}\left(1+1/x\right)^x\approx 2.718281828

The second, also known as the 'Euler-Mascheroni Constant' and commonly symbolized by \gamma is
\gamma=\lim_{x\to\infty}\left(\sum_{k=1}^x {\frac{1}k} - \ln x\right)\approx0.577215665
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PostPosted: Thu Mar 17, 2005 1:16 am
Nomendil
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#4
In my experience, e is generally referred to as the "euler number" rather than as his constant.

PostPosted: Thu Mar 17, 2005 12:06 pm
Magnara
Yang-Mills Theory
Yang-Mills Theory

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#5
Mascheroni sounds more like a noodle than a constant.

And I've usually seen e referred to as the exponential constant. That's what the e stands for, not "Euler."
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PostPosted: Thu Mar 17, 2005 11:57 pm
Celeborn
Hodge Conjecture
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#6
Magnara wrote:
Mascheroni sounds more like a noodle than a constant.

And I've usually seen e referred to as the exponential constant. That's what the e stands for, not "Euler."


That's probably not true either. I read that Euler used "e" because it was the next unused letter of the alphabet (I'm not sure what the previous letters were taken up for) , and it stuck.

PostPosted: Mon Mar 21, 2005 2:32 am
billzhao
Yang-Mills Theory
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#7
Actually, e is more often known as the Napier's constant.
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PostPosted: Mon Mar 21, 2005 3:11 am
ComplexZeta
Birch & Swinnerton Dyer
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#8
I hadn't heard e referred to as Napier's constant before, but if Napier deserves his name on any constant, it would be 1/e rather than e itself. (His logarithms were essentially in base 1/e, except he used 10 million for \infty.)
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PostPosted: Mon Mar 21, 2005 8:02 am
problem_solver
P versus NP
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#9
Danbert wrote:
Euler has the distinction of being (maybe?) the only person with two constants named after him. The first, e , is
e=\lim_{x\to\infty}\left(1+1/x\right)^{x}\approx 2.718281828
The second, also known as the 'Euler-Mascheroni Constant' and commonly symbolized by \gamma is
\gamma=\lim_{x\to\infty}\left(\sum_{k=1}^{x}{\frac{1}k}-\ln x\right)\approx0.577215665


How would you prove that this sequence converges:

\gamma=\lim_{x\to\infty}\left(\sum_{k=1}^{x}{\frac{1}k}-\ln x\right)\approx0.577215665

\frac{1}{1}+\frac{1}{2}+\frac{1}{3}+....+\frac{1}{n}-log(n) ?

To start, I know that

\frac{1}{1}+\frac{1}{2}+\frac{1}{3}+....+\frac{1}{n} diverges as n gets very large, and so does log(n)

But together, how how you prove that the difference of these two converges?

PostPosted: Thu Mar 01, 2007 12:31 am
Treething
Navier-Stokes Equations
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#10
well...

\frac{1}{2}+\frac{1}{3}+...+\frac{1}{n}-\log(n)

is really the same as

(\frac12-\log\frac21)+(\frac13-\log\frac32)+...+(\frac1n-\log\frac{n}{n-1})



just speculating, the mathworld link probably has more in-depth and more correct information but i'm too lazy to decipher math language into english
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PostPosted: Thu Mar 01, 2007 5:01 am
paladin8
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#11
\sum_{k=1}^{x}\frac{1}{k}< 1+\int_{1}^{x}\frac{dt}{t} so we know the limit of the difference is less than 1 (and also that it is positive by a similar argument).
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PostPosted: Thu Mar 01, 2007 7:59 am
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