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20000915: defining scalar variables

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  • Subject: 20000915: defining scalar variables
  • Date: Fri, 15 Sep 2000 11:21:07 -0600
Stefan,

> To: address@hidden
> From: Stefan Maehlmann <address@hidden>
> Subject: netcdf problem
> Organization: UCAR/Unidata
> Keywords: 200009151648.e8FGmtb07020

The above message contained the following:

> i'm new with netcdf. But for most things, i tried up to now i works fine.
> However i have a problem treating scalars and arrays:
> I want to write a simple scalar value to a file and then an array. So i coded
> up the following lines: 
> ....
> 
> 
> integer, parameter :: time_rank = 0, &
>                              val_rank = 2
> integer val_dims (val_rank)
> 
> ....
> 
> status = nf_def_var_double (ncid, 'time',nf_double,time_rank,0,time_id) 
> if (status.ne.0) then ...
> 
> status = nf_def_var_double (ncid,'val',nf_double,val_rank, val_dims,val_id)
> 
> if (status.ne.0) then ...
> ....
> 
> The compiler (NAG f95) says: 
> 
> .... inconstant structure for arg 5 in call to nf_def_var_double ...
> 
> So there is a difference if i set the dim value in the function
> nf_def_var_double to zero which should repreesent a scalar an for
> examples to 2 (2-dim array)
>
> I don't know how to solve the problem in handling scalar and array. So
> i please you to help me
> 
> Thanx in advance,
> 
> Stefan Maehlmann 
> ------------------------------------
>            Stefan Maehlmann               Email:   address@hidden 
> Aerodynamisches Institut der RWTH-Aachen  WWW: http://www.aia.rwth-aachen.de
>       Wuellnerstr. zw. 5 u. 7             Ftp:  ftp://ftp.aia.rwth-aachen.de
>       D-52062 Aachen, Germany   Phone: +49-241-80-5426 Fax: +49-241-8888-257

First off, you should used the function "nf_def_var" rather than 
"nf_def_var_double".

Here's how to do what you want:

    integer, parameter :: time_rank = 0, & val_rank = 2
    integer val_dims (val_rank)
    status = nf_def_var(ncid,'time',nf_double,time_rank,val_dims,time_id) 
    status = nf_def_var(ncid,'val',nf_double,val_rank,val_dims,val_id)

The key issue is that the dimension-array argument must have the same
type in both calls (i.e. it must be a vector of integers).  The argument
will be ignored in the scalar case (i.e. where the rank is zero).

Regards,
Steve Emmerson   <http://www.unidata.ucar.edu>