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## #26 2011-07-25 01:36:50

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi;

Have you asked sage what that product is, just to see?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #27 2011-07-25 01:48:19

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Sage supports product only for a list of numbers, not infinite product, I guess.

But I tested it in wolfram, the product is correct.

Last edited by gAr (2011-07-25 01:48:40)

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #28 2011-07-25 01:53:05

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi gAr;

Did you get

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #29 2011-07-25 01:59:38

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Hi,

Yes.

The form it showed is:

It had gamma functions in the partial product formula.

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #30 2011-07-25 02:39:16

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi gAr;

I am not getting anywhere with that product.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #31 2011-07-25 03:02:35

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Hi bobbym,

Okay.
Anyway, I could get somewhere with that integral!
It's explained in Richard courant's book, "Differential and integral calculus" vol II

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #32 2011-07-25 03:22:15

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi gAr;

Very good! Thanks for providing that.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #33 2011-07-25 04:07:40

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

You're welcome!

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #34 2011-07-25 18:01:06

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

I finally finished the D Knuth video without interruption. It was very enjoyable.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #35 2011-07-25 18:03:57

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Hi,

So, the full problem was to evaluate:

and the

Hi bobbym,

Yes, I too enjoyed the video!

Last edited by gAr (2011-07-25 18:05:41)

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #36 2011-07-25 18:11:34

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi gAr;

Did you submit the solution to that page yet?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #37 2011-07-25 18:16:18

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Hi bobbym,

No, I didn't.
Did he solve it, and didn't post the solution because it isn't published yet?

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #38 2011-07-25 18:23:48

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi gAr;

I do not know. I did not find a solution to that problem anywhere on the net. Yours might be unique.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #39 2011-07-25 18:29:00

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Hmmm, okay.

The first problem that I have solved from the monthly!
Anyway, since it isn't free, we may not find it on the net.

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #40 2011-07-25 18:31:31

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi gAr;

Sometimes you can. That crazy integral was on the internet. That is where I got his pdf.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #41 2011-07-25 18:35:06

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Hi,

That's true.

But it's very difficult to search for equations, since mathematical operatos are ignored or have a different meaning for the search engines.

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #42 2011-07-25 18:36:44

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

Hi gAr;

Search by the AM number, each problem has one.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #43 2011-07-25 18:39:42

gAr
Member
Registered: 2011-01-09
Posts: 3,481

### Re: Exponential integral

Hi,

Yes, for this case we can search something.
I'm telling in general, where we know only the equation or integral etc.

I'll take a short break, see you later.

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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## #44 2011-07-25 18:42:21

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Exponential integral

That is generally true it is very hard to get Google to understand.

See you soon.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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