What x86_64-pc-linux-gnu is?

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What x86_64-pc-linux-gnu is?

Leloup
Bonjour,

    When launching the named command "computer", Octave answers:
"x86_64-pc-linux-gnu". What does that mean? Octave works only with 32 bits
while Windows runs fully with 64 bits. Isn't?
What answer should be expected if Octave fully worked with 64bits?

Regards,

Michel



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Re: What x86_64-pc-linux-gnu is?

Sergei Steshenko


On Sunday, September 16, 2018, 10:45:12 AM GMT+3, Leloup <[hidden email]> wrote:


Bonjour,

    When launching the named command "computer", Octave answers:
"x86_64-pc-linux-gnu". What does that mean? Octave works only with 32 bits
while Windows runs fully with 64 bits. Isn't?
What answer should be expected if Octave fully worked with 64bits?

Regards,

Michel



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--Sergei.





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Re: What x86_64-pc-linux-gnu is?

Leloup
Bonjour Sergei,

Thank you for your email

>> uname()
ans =

  scalar structure containing the fields:

    sysname = Linux
    nodename = Leloup-VirtualBox
    release = 4.10.0-38-generic
    version = #42~16.04.1-Ubuntu SMP Tue Oct 10 16:32:20 UTC 2017
    machine = x86_64

I don't get more information.

Regards,

Leloup






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Re: What x86_64-pc-linux-gnu is?

Mike Miller-4
In reply to this post by Leloup
On Sun, Sep 16, 2018 at 02:44:10 -0500, Leloup wrote:
>     When launching the named command "computer", Octave answers:
> "x86_64-pc-linux-gnu". What does that mean? Octave works only with 32 bits
> while Windows runs fully with 64 bits. Isn't?
> What answer should be expected if Octave fully worked with 64bits?

What do you mean by "fully worked with 64bits?"

The "x86_64" means that Octave is compiled to Intel 64-bit architecture
and instruction sets.

If you mean whether Octave can use 64-bit integer indexing, you can
determine that by looking at what the 'sizemax' function returns.

    >> help sizemax
    …
         Return the largest value allowed for the size of an array.
    …
    >> sizemax
    ans = 9223372036854775806

--
mike



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Re: What x86_64-pc-linux-gnu is?

Leloup
Bonjour Mike,

         Clear.    
         Thank you for answer.

Regards,

Leloup



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Re: What x86_64-pc-linux-gnu is?

Leloup
Mike,

look at

>> format long
>> log2(9223372036854775806)
ans =  63 for 64bits
>> 2^63
ans =  9223372036854775808  

Difference is around 2. Normally, that should be either 9223372036854775806
or 9223372036854775808.

>> sizemax
ans = 2147483646
>> log2(2147483646)
ans =  30.9999999986564  ~ 31 for 32bits

So your PC correctly works with 64bits while mine with 32bits. So, something
is wrong for my PC.

Regards,
Leloup




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Re: What x86_64-pc-linux-gnu is?

Mike Miller-4
On Wed, Sep 19, 2018 at 14:15:58 -0500, Leloup wrote:
> Difference is around 2. Normally, that should be either 9223372036854775806
> or 9223372036854775808.

That's correct, my 'sizemax' returns 2**63 - 2.

> >> sizemax
> ans = 2147483646
> >> log2(2147483646)
> ans =  30.9999999986564  ~ 31 for 32bits

That's correct, your 'sizemax' returns 2**31 - 2.

> So your PC correctly works with 64bits while mine with 32bits. So, something
> is wrong for my PC.

No, not necessarily. These are both valid and correct answers, the value
depends on the version of Octave and how it was configured.

You initially asked what the symbol "x86_64" means, and I suggested
looking at the return value of 'sizemax' to additionally determine the
range of indexing. I was guessing at what you meant by the qualifier
"fully".

Are you now asking how to install a version of Octave that supports
arrays with 64 bit indexes? Are you sure that you need that?

--
mike



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Re: What x86_64-pc-linux-gnu is?

Leloup
Bonjour Mike,

      " Are you sure that you need that? "  Clever remark
      " how to install a version of Octave that supports arrays with 64 bit
indexes? " I suppose when installing Octave, I probably lacked of attention.
It was supposed to be offered and I missed it.
      sizemax is a good way to check it.

       however if you have any advice, it's always good to take.  

Best regards,

Leloup



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Re: What x86_64-pc-linux-gnu is?

Mike Miller-4
On Thu, Sep 20, 2018 at 12:53:53 -0500, Leloup wrote:
>       " Are you sure that you need that? "  Clever remark

It's an honest question. Are you sure that you need to create arrays
with over 2 billion elements? I don't.

>       " how to install a version of Octave that supports arrays with 64 bit
> indexes? " I suppose when installing Octave, I probably lacked of attention.
> It was supposed to be offered and I missed it.
>       sizemax is a good way to check it.
>
>        however if you have any advice, it's always good to take.  

I'm not sure what your objective is at this point. If you have Octave
installed and it's working for you, then there's nothing to do.

If you do honestly need to work with large arrays with more than 2
billion elements, then you will need to install Octave again to take
care of that. What GNU/Linux distribution are you using? How did you
install Octave, from source or from the distro package system? What
version of Octave do you have installed?

If you have Octave 4.4 or newer, it should support 64 bit indexes by
default on a 64 bit processor.

--
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SOLVED: What x86_64-pc-linux-gnu is?

Leloup

       Thank you Mike
        I appreciated the accuracy of your answers.

Regards,

Leloup



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