[ncl-talk] regCoef_n without y-axis intercept

[Giorgio Graffino]

Hi Dave,

Thanks for confirming that. I'm changing the fortran subroutine Dennis 
sent last week into a function, but it keeps giving me an error wherever 
I try to use arrays as arguments. It only works when X and Y are scalar 
numbers. I really don't understand how a linear regression fit can be 
found with scalar numbers as arguments. I'm looking at the C interface 
to see how to subroutine is called, but there are too many things 
happening in regcoefW.c and it's difficult to understand the workflow. 
Can anyone please help me understand how to make the fortran subroutine 
work for 1d and 2d arrays?

Cheers,
Giorgio


    ------ Messaggio Originale ------
    Da: dave.allured at noaa.gov
    A: g.graffino at tim.it
Cc: ncl-talk at ucar.edu
    Inviato: lunedì 24 ottobre 2022 22:10
    Oggetto: Re: [ncl-talk] regCoef_n without y-axis intercept


Giorgio, you are right, regcoefW.c is an NCL internal interface routine 
for regCoef_n.  But it uses a different protocol than a WRAPIT 
interfaced function.  Just ignore regcoefW.c, and follow the WRAPIT 
fortran instructions carefully, for your new function.  Change the 
function name, and do not attempt to replace the built-in regCoef_n 
function.  You can change the arguments as you like, but follow the 
documented WRAPIT rules.

There are two different methods for calling external C functions: 
fortran wrapper, and shared object.  Please study the WRAPIT 
documentation carefully.


On Mon, Oct 24, 2022 at 1:35 PM Giorgio Graffino via ncl-talk 
<ncl-talk at mailman.ucar.edu <mailto:ncl-talk at mailman.ucar.edu> > wrote:

Hello,
I'm doing some modifications to the regcoef_dp.f file to consider a zero 
y-intercept, but now I don't know how to try it in a script. The number 
of arguments in the fortran subroutine is different than in regCoef_n, 
so the subroutine is probably going through some more steps, possibly 
involving this script 
(https://github.com/NCAR/ncl/blob/develop/ni/src/lib/nfp/regcoefW.c 
<https://github.com/NCAR/ncl/blob/develop/ni/src/lib/nfp/regcoefW.c> ). 
Am I right?
How can I incorporate both fortran and C scripts in my NCL script? I 
know I can use WRAPIT to read external fortran code, but what about C 
code?
I need help please.
Giorgio
    ------ Messaggio Originale ------
    Da: ncl-talk at mailman.ucar.edu <mailto:ncl-talk at mailman.ucar.edu>
    A: shea at ucar.edu <mailto:shea at ucar.edu>
Cc: ncl-talk at ucar.edu <mailto:ncl-talk at ucar.edu>
    Inviato: venerdì 21 ottobre 2022 13:14
    Oggetto: Re: [ncl-talk] regCoef_n without y-axis intercept

         Hi Dennis, Dave
Thanks for sending the relevant function and for explaining how to 
access the source code. Now I'm thinking how to make the function to 
force the regression to pass from origin. Any idea on how to do that?
Cheers,
Giorgio
------ Messaggio Originale ------
    Da: shea at ucar.edu <mailto:shea at ucar.edu>
    A: g.graffino at tim.it <mailto:g.graffino at tim.it>
Cc: dave.allured at noaa.gov <mailto:dave.allured at noaa.gov> ; 
ncl-talk at ucar.edu <mailto:ncl-talk at ucar.edu>
    Inviato: giovedì 20 ottobre 2022 19:17
    Oggetto: Re: [ncl-talk] regCoef_n without y-axis intercept


The f77 code is attached.



On Thu, Oct 20, 2022 at 9:53 AM Giorgio Graffino via ncl-talk 
<ncl-talk at mailman.ucar.edu <mailto:ncl-talk at mailman.ucar.edu> > wrote:

Hi Dave,

Thanks for the advice. I looked at the examples in 
https://www.ncl.ucar.edu/Applications/regress.shtml 
<https://www.ncl.ucar.edu/Applications/regress.shtml> , especially 
examples 2 and 4, but I couldn't find any supplementary information 
about regCoef. I also can't find anything under 
$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl and 
$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl.
Is NCL source code located anywhere in $NCARG_ROOT? Can anyone please 
point me where it is?
Cheers,
Giorgio

------ Messaggio Originale ------
    Da: dave.allured at noaa.gov <mailto:dave.allured at noaa.gov>
    A: g.graffino at tim.it <mailto:g.graffino at tim.it>
Cc: ncl-talk at ucar.edu <mailto:ncl-talk at ucar.edu>
    Inviato: giovedì 13 ottobre 2022 18:47
    Oggetto: Re: [ncl-talk] regCoef_n without y-axis intercept


Giorgio, for your second question, please see this very brief 
description that I recently wrote, for how to search for functions in 
the NCL source code.
https://mailman.ucar.edu/pipermail/ncl-talk/2022-August/018954.html 
<https://mailman.ucar.edu/pipermail/ncl-talk/2022-August/018954.html>



On Thu, Oct 13, 2022 at 10:38 AM Giorgio Graffino via ncl-talk 
<ncl-talk at mailman.ucar.edu <mailto:ncl-talk at mailman.ucar.edu> > wrote:

Hi NCL community,
I want regCoef_n to find the regression coefficient between two arrays 
without y-axis intercept. Do you know how I can change the function to 
do that?
Can you also please tell me where I can find the function? I did a grep 
recursive search in my $NCARG_ROOT directory but I couldn't find it.
Cheers,
Giorgio









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