date:20220525

[Scilab-users] mailing lists archive and subscription disabled

2022-05-25 Thread CHEZE David 227480

Hi,

It's not possible anymore to browse or to subscribe to users mailing lists from 
the links displayed in Scilab website 
https://www.scilab.org/about/community/mailing-lists
And search on lists.scilab.org domain doesn't return clear location of the 
archive. This issue was already raised a few years ago and is for sure reason 
for preventing new unregistered users to take part to the community, to get 
support from community and to suggest .
Is ESI still taking care of keeping Scilab and its website alive in any way ?

David

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Re: [Scilab-users] mailing lists archive and subscription disabled

2022-05-25 Thread Stéphane Mottelet


Hi David,

Le 25/05/2022 à 10:28, CHEZE David 227480 a écrit :


Hi,

It’s not possible anymore to browse

Yes, I already gave a solution to this problem, the list is also 
archived there:


https://www.mail-archive.com/users@lists.scilab.org

the whole thread is available at

https://www.mail-archive.com/users@lists.scilab.org/msg10628.html

or to subscribe to users mailing lists from the links displayed in 
Scilab website https://www.scilab.org/about/community/mailing-lists 



You are not right, the subscription links work 
(http://lists.scilab.org/mailman/listinfo/users)


And search on lists.scilab.org domain doesn’t return clear location of 
the archive. This issue was already raised a few years ago and is for 
sure reason for preventing new unregistered users to take part to the 
community, to get support from community and to suggest .


Is ESI still taking care of keeping Scilab and its website alive in 
any way ?


I don't know (although I am very concerned about Scilab, I don't work at 
ESI...). I hope that the situation will be clarified before the end of 
2022.


S.


David


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--
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet
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Re: [Scilab-users] Riemann Zeta update

2022-05-25 Thread Stéphane Mottelet


Hi,

For real argument, we could easily interface std::riemann_zeta :

https://en.cppreference.com/w/cpp/numeric/special_functions/riemann_zeta

If you have a compiler (under windows you can install the minGW atoms 
module), you can run the following script:


code=[
"#define __STDCPP_WANT_MATH_SPEC_FUNCS__ 1 "
"#include "
"#include ""double.hxx"" "
"#include ""function.hxx"" "
"extern ""C"" "
"{ "
"#include ""Scierror.h"" "
"#include ""localization.h"" "
"} "
"/*  
*/ "
"types::Function::ReturnValue sci_zeta(types::typed_list &in, int 
_iRetCount, types::typed_list &out) "

"{ "
"types::Double* pDblOut; "
"types::Double* pDblIn; "
"if (in.size() != 1) "
"{ "
"Scierror(77, _(""%s: Wrong number of input argument(s): %d 
expected.\n""), ""zeta"", 1); "

"return types::Function::Error; "
"} "
"if (_iRetCount >1) "
"{ "
"Scierror(78, _(""%s: Wrong number of output argument(s): %d 
expected.""), ""zeta"", 1); "

"return types::Function::Error; "
"} "
"if (in[0]->isDouble() == false || 
in[0]->getAs()->isComplex()) "

"{ "
"Scierror(999, _(""%s: Wrong type for input argument #%d: real 
expected.\n""), ""zeta"", 1); "

"return types::Function::Error; "
"} "
"pDblIn = in[0]->getAs(); "
"pDblOut = pDblIn->clone(); "
"for (int i = 0 ; i getSize() ; ++i) "
"{ "
"pDblOut->set(i,std::riemann_zeta(pDblIn->get(i))); "
"} "
"out.push_back(pDblOut); "
"return types::Function::OK; "
"} "
];
ulink
files  =  fullfile(TMPDIR,"sci_zeta.cpp");
mputl(code,files)
ilib_verbose(1)
ilib_build("zeta",  ["zeta"  "sci_zeta"  "cppsci"],files,[])
exec  loader.sce

tic
disp(zeta(0.5))
disp(toc())


Le 22/05/2022 à 08:31, Lester Anderson a écrit :

Hi all,

After a lot of trial and error, I have managed to get a set of 
functions to compute the approximations of Riemann's Zeta for negative 
and positive real values; values of n > 1e6 seem to give better results:


function  zs=zeta_s(z, n)
 // Summation loop
 zs=1;
 if  z  ==  0  
zs  =  -0.5

 elseif  z  ==  1
zs  =  %inf
 else
 for  i  =  2:  n-1
 zs  =  zs  +  i.^-z;
 end
 end
endfunction

function  zfn=zeta_functional_eqn(s)
// Riemann's functional equation
// Analytic continuation for negative values
 zfn  =  2.^s  .*  %pi.^(s  -  1)  .*  sin(%pi.*s./2)  .*  gamma(1  -  s)  
.*  zeta_s((1  -  s),n)
endfunction
For even values of s < -20 the values of Zeta(s) increase in value and 
are not as close to zero as expected e.g. zeta_functional_eqn(-40) 
gives 7.5221382. At small even values e.g. -10, the result is of the 
order of ~1e-18 (close enough to zero). Any ideas why the even zeta 
values increase or how to reduce that response?


The solution over the critical strip (zero to one) is not so efficient 
unless n is very large( > 1e8), and there seems to be a performance 
issue when using a for-loop compared to vectorisation. Vectorised n 
speeds things up quite a bit.


function  zs2=zeta_0_1(s, n)
zs2=0
for  i  =  1:  n
  zs2  =  zs2  +  (-1).^(i  +  1)./(i.^s  );
end
  zs2  =  1./(1  -  2.^(  1-s  )).*zs2; 
endfunction


function  zs1=zeta_0_1(s, n)
// Vectorised version
zs1=0
k=linspace(1,n,n);
   zs1  =  sum((-1).^(k+  1)./(k.^s  ));
   zs1  =  1./(1  -  2.^(  1-s  )).*zs1;
endfunction
For example, calculating the approximation of Zeta(0.5) using a 
for-loop takes ~150s to give a value of -1.4602337981325388 (quite 
close), whereas the vectorised version does the computation in under 
20s, both tested using n=1e8. Can the functions be optimised to 
improve speed and accuracy?


Using Scilab 6.1.1 on Windows 10 (16 Gb RAM).

Thanks
Lester

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--
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet
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Re: [Scilab-users] mailing lists archive and subscription disabled

2022-05-25 Thread CHEZE David 227480

Thank you for your reply Stephane,
unfortunately the subscription link doesn’t work from my side WIN10-Chrome.
[cid:image002.png@01D8702B.14D297C0]

Since the link to the actual mail archive repository is not referenced on the 
Scilab.org website, very limited chance that any unregistered user manage to 
find it : is anyone from ESI looking at this thread to update the website ?

Regards,

David


De : users  De la part de Stéphane Mottelet
Envoyé : mercredi 25 mai 2022 11:02
À : users@lists.scilab.org
Objet : Re: [Scilab-users] mailing lists archive and subscription disabled


Hi David,
Le 25/05/2022 à 10:28, CHEZE David 227480 a écrit :
Hi,

It’s not possible anymore to browse

Yes, I already gave a solution to this problem, the list is also archived there:

https://www.mail-archive.com/users@lists.scilab.org

the whole thread is available at

https://www.mail-archive.com/users@lists.scilab.org/msg10628.html
or to subscribe to users mailing lists from the links displayed in Scilab 
website 
https://www.scilab.org/about/community/mailing-lists
You are not right, the subscription links work 
(http://lists.scilab.org/mailman/listinfo/users)

And search on lists.scilab.org domain doesn’t return clear location of the 
archive. This issue was already raised a few years ago and is for sure reason 
for preventing new unregistered users to take part to the community, to get 
support from community and to suggest .
Is ESI still taking care of keeping Scilab and its website alive in any way ?

I don't know (although I am very concerned about Scilab, I don't work at 
ESI...). I hope that the situation will be clarified before the end of 2022.

S.

David




___

users mailing list

users@lists.scilab.org

https://antispam.utc.fr/proxy/v3?i=WG91eXZybW45Ym1EZEZCbdLWaANujcLcgsFkB3F7dzg&r=bnJjU3hQT3pQSmNQZVE3aHi0e9tBMT9ll7ukw_G-zVkmPCTRUjeyB5560oG7uBEr&f=SGI0YVJGNmxZNE90Z2thMND4NUJUIHsVzjiyBeFmyAEyW-lenoPpNM8ZjDD6Ns-Z&u=http%3A//lists.scilab.org/mailman/listinfo/users&k=JI69

--

Stéphane Mottelet

Ingénieur de recherche

EA 4297 Transformations Intégrées de la Matière Renouvelable

Département Génie des Procédés Industriels

Sorbonne Universités - Université de Technologie de Compiègne

CS 60319, 60203 Compiègne cedex

Tel : +33(0)344234688

http://www.utc.fr/~mottelet
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[Scilab-users] HDF5 write data to file

2022-05-25 Thread Lester Anderson

Hi all,

I just found a useful way of getting netCDF files into Scilab via HDF5
(just found this!):

a=h5open('Test_10-FAA.grd');
h5ls(a)
//  "lat" "dataset"  //  "lon"
"dataset"  //  "z"   "dataset"  //  "Conventions"
"attribute"//  "GMT_version" "attribute"//  "_NCProperties"
"attribute"//  "description""attribute"//  "history"
   "attribute"//  "node_offset"   "attribute"//  "title"
"attribute"
lon=h5read(a, 'lon');lat=h5read(a, 'lat');data=h5read(a, 'z');

h5close(a);

The data plots fine via Sgrayplot(lon,lat,data,zminmax=[-25,25]) . I need
to know how to write data out to essentially replicate the input netCDF
file, so any pointers/examples would be helpful. It would be good to output
a file in a format that GMT (Generic Mapping Tools) would recognise.

The use of HDF5 seems to solve the issues of working with netCDF-4 files.

Lester
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[Scilab-users] mailing lists archive and subscription disabled

Re: [Scilab-users] mailing lists archive and subscription disabled

Re: [Scilab-users] Riemann Zeta update

Re: [Scilab-users] mailing lists archive and subscription disabled

[Scilab-users] HDF5 write data to file

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