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A mistake in the wolfram mathworld website

ZaidAlyafey

Well-known member
MHB Math Helper
Jan 17, 2013
1,667
I was proving a formula for the hypergoemtric function and noticed that there is a mistake in the following page look at equation (1) and compare it to equation (16) in the following page . Is there a way to correct the mistake ?
 
Last edited:

mathbalarka

Well-known member
MHB Math Helper
Mar 22, 2013
573
I often come up with a whole lot of mistakes on that particular site.

Look at the leftmost edge of the page and you'll see a tool to send message to the editorial board. Quote the line you feel is incorrect, then send them that.
 

Sudharaka

Well-known member
MHB Math Helper
Feb 5, 2012
1,621
I was proving a formula for the hypergoemtric function and noticed that there is a mistake in the following page look at equation (1) and compare it to equation (16) in the following page . Is there a way to correct the mistake ?
Hi Zaid, :)

Both of your links refer to the same page. :)
 

ZaidAlyafey

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MHB Math Helper
Jan 17, 2013
1,667

topsquark

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MHB Math Helper
Aug 30, 2012
1,123

Klaas van Aarsen

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Staff member
Mar 5, 2012
8,780
Hey, WolframAlpha still thinks that the integral of 1/x is log(x).

-Dan
What's wrong with that? ;)

Actually W|A gives $\log(x) + \color{gray}{\text{constant}}$.
And isn't that true for all $x>0$? It's not as if W|A gives a domain.
Isn't it also true for all $x \in \mathbb C^*$?
Anyway, even in the real numbers it is properly:
\begin{cases}\ln x + C_1 & \text{if } x>0 \\ \ln(-x) + C_2 & \text{if } x<0 \end{cases}

I think that W|A prefers complex numbers, or otherwise would probably still not give such a convoluted answer. :rolleyes:
 

Random Variable

Well-known member
MHB Math Helper
Jan 31, 2012
253
You have to somehow tell Wolfram Alpha that $x$ is a real variable. Otherwise it will assume that $x$ is a complex variable. And if $x$ is a complex variable, $\displaystyle \int \frac{1}{x} \ dz = \log(x) + C$ is a true statement.
 

topsquark

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MHB Math Helper
Aug 30, 2012
1,123
You have to somehow tell Wolfram Alpha that $x$ is a real variable. Otherwise it will assume that $x$ is a complex variable. And if $x$ is a complex variable, $\displaystyle \int \frac{1}{x} \ dz = \log(x) + C$ is a true statement.
Good point. Not to hijack the thread but can you quickly tell me how you would tell Wolfram x is real?

-Dan
 

Random Variable

Well-known member
MHB Math Helper
Jan 31, 2012
253
For whatever reason, I am unable to link directly to the Wolfram Alpha output.

But the following command seems to return nonsense.

assuming[Element[x, Reals] , int [1/x,x]]
 

Sawarnik

New member
Mar 28, 2014
7
I often come up with a whole lot of mistakes on that particular site.

Look at the leftmost edge of the page and you'll see a tool to send message to the editorial board. Quote the line you feel is incorrect, then send them that.

Yeah, right. An awful lot of mistakes. I once tried that send message and sent the error and correction but no one looked at it, and remains incorrect today as well, and so I think its useless. In fact, I think Wikipedia is less error-prone than Mathworld.
 

Klaas van Aarsen

MHB Seeker
Staff member
Mar 5, 2012
8,780
Yeah, right. An awful lot of mistakes. I once tried that send message and sent the error and correction but no one looked at it, and remains incorrect today as well, and so I think its useless. In fact, I think Wikipedia is less error-prone than Mathworld.
Which mistake?
 

Sawarnik

New member
Mar 28, 2014
7
So where is the mistake in that article?
"and Brahmagupta's formula for the area of a quadrilateral:"

Is the formula after that Brahmagupta's!
 

Klaas van Aarsen

MHB Seeker
Staff member
Mar 5, 2012
8,780
Hmm, so the math is perfectly correct and as such MathWorld is reliable.
The problem is that the credits given are not correct in that article.
Just now, I have sent a contribution to MathWorld with the suggestion to correct this.
We'll see.
 

mathbalarka

Well-known member
MHB Math Helper
Mar 22, 2013
573
IlikeSerena said:
Hmm, so the math is perfectly correct and as such MathWorld is reliable.
At least, more than wikipedia in any case.
 

Klaas van Aarsen

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Mar 5, 2012
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mathbalarka

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MHB Math Helper
Mar 22, 2013
573
Where is the mistake in wikipedia?
Somehow, I knew you'd say that. There have been many changes in wiki since I saw them, so I will show you only the ones I can find.

First, I remember wiki giving a terribly false estimate for the totient sum

$$\sum_{n\leq x} \frac1{\varphi(n)}$$

Which I don't remember what it was and they corrected it afterwards, as I see it.

Second is something on tetration, I haven't seen whether it is still there but I can't rember it either.

The last is Von Mangoldt. It's fresh as new and you can see all the craps there if you open the page up.
 

Sawarnik

New member
Mar 28, 2014
7
Hmm, so the math is perfectly correct and as such MathWorld is reliable.
The problem is that the credits given are not correct in that article.
Just now, I have sent a contribution to MathWorld with the suggestion to correct this.
We'll see.
No, the formula named is wrong, which is problematic.
And I had already sent a message to them, but there has been no corrections!

- - - Updated - - -

At least, more than wikipedia in any case.
But you can correct errors in Wiki with no prob. The MathWorld team however never listens to any suggestion and the mistake remain mistakes.

But form my experience Wiki is not at all as bad as people say.