Re: [sage-support] Integral result differ from Wolfram|Alpha

2023-11-13 Thread Oscar Benjamin
On Mon, 13 Nov 2023 at 21:32, Bùi Gia Nghĩa  wrote:
>
> Hi!
> I have used Sage Cell Server to integrate the function (ln(x)^2 - 1) / (x * 
> ln(x)). It should resulted in (ln(x)^2) / 2 - |ln(ln(x))| + C, as noted by my 
> textbook and Wolfram|Alpha, but instead resulted in 1/2*log(x)^2 - 
> 1/2*log(log(x)^2).

Your textbook assumes that you are only interested in real
antiderivatives and so describes the antiderivative with abs that is
not complex-differentiable (i.e. not valid for non-real values of x).
The result from Sage is valid for e.g. x = 1+i whereas your textbook
result would be incorrect in that case.

--
Oscar

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Re: [sage-support] Re: Integral result differ from Wolfram|Alpha

2023-11-13 Thread Bùi Gia Nghĩa
Oh that's why! Thank you because that is exactly the problem!

On Tue, Nov 14, 2023, 4:54 AM John H Palmieri 
wrote:

> Isn't log(log(x)^2) = 2 * log(log(x))? Is this your concern, or is it the
> absolute value?
>
> On Monday, November 13, 2023 at 1:32:11 PM UTC-8 Bùi Gia Nghĩa wrote:
>
>> Hi!
>> I have used Sage Cell Server to integrate the function (ln(x)^2 - 1) / (x
>> * ln(x)). It should resulted in (ln(x)^2) / 2 - |ln(ln(x))| + C, as noted
>> by my textbook and Wolfram|Alpha, but instead resulted in 1/2*log(x)^2 -
>> 1/2*log(log(x)^2).
>> (I do notice that SageMath use log(a) to denote natural logarithm, so
>> that's not the question here).
>> Anyone knows why it happen? I think that this is a bug from some system
>> SageMath use to calculate this, but I am new to SageMath so have zero
>> knowledge about the system.
>> Here is the exact code I input:
>> var("x")
>> f = (log(x)**2 - 1) / (x * log(x))
>> integral(f, x)
>>
>> Thanks in advance!
>>
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> .
>

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[sage-support] Re: Integral result differ from Wolfram|Alpha

2023-11-13 Thread John H Palmieri
Isn't log(log(x)^2) = 2 * log(log(x))? Is this your concern, or is it the 
absolute value?

On Monday, November 13, 2023 at 1:32:11 PM UTC-8 Bùi Gia Nghĩa wrote:

> Hi!
> I have used Sage Cell Server to integrate the function (ln(x)^2 - 1) / (x 
> * ln(x)). It should resulted in (ln(x)^2) / 2 - |ln(ln(x))| + C, as noted 
> by my textbook and Wolfram|Alpha, but instead resulted in 1/2*log(x)^2 - 
> 1/2*log(log(x)^2). 
> (I do notice that SageMath use log(a) to denote natural logarithm, so 
> that's not the question here).
> Anyone knows why it happen? I think that this is a bug from some system 
> SageMath use to calculate this, but I am new to SageMath so have zero 
> knowledge about the system.
> Here is the exact code I input:
> var("x")
> f = (log(x)**2 - 1) / (x * log(x))
> integral(f, x)
>
> Thanks in advance!
>

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[sage-support] Integral result differ from Wolfram|Alpha

2023-11-13 Thread Bùi Gia Nghĩa
Hi!
I have used Sage Cell Server to integrate the function (ln(x)^2 - 1) / (x * 
ln(x)). It should resulted in (ln(x)^2) / 2 - |ln(ln(x))| + C, as noted by 
my textbook and Wolfram|Alpha, but instead resulted in 1/2*log(x)^2 - 
1/2*log(log(x)^2). 
(I do notice that SageMath use log(a) to denote natural logarithm, so 
that's not the question here).
Anyone knows why it happen? I think that this is a bug from some system 
SageMath use to calculate this, but I am new to SageMath so have zero 
knowledge about the system.
Here is the exact code I input:
var("x")
f = (log(x)**2 - 1) / (x * log(x))
integral(f, x)

Thanks in advance!

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