NAME

       ncflint - netCDF File Interpolator

SYNTAX

       ncflint  [-3]  [-4]  [-6]  [-7]  [-A]  [--bfr  sz][-C][-c][-D  dbg_lvl]  [-d  dim,[  min][,[  max]]] [-F]
       [--fix_rec_crd] [-G gpe_dsc] [-g grp[,...]]  [-h] [--hdf] [--hdr_pad  sz]  [-i  var,val3][-L  dfl_lvl][-l
       path] [--msa] [--no_tmp_fl] [-O] [-p path] [-R] [-r] [--ram_all] [-t thr_nbr] [--unn] [-v var[,...]]  [-w
       wgt[, wgt2]] [-X box] [-x] file1 file2 file3

DESCRIPTION

       ncflint creates an output file that is a linear combination of the input files.  This linear  combination
       can  be  a  weighted  average,  a  normalized  weighted  average, or an interpolation of the input files.
       Coordinate variables are not acted upon in any case, they are simply copied from file_1.
        There are two conceptually distinct methods of using ncflint.  The first method is to specify the weight
       each  input  file  is  to  have  in the output file.  In this method, the value val3 of a variable in the
       output file file_3 is determined from its values val1 and val2  in  the  two  input  files  according  to
       wgt1*val1+wgt2*val2

       Here  at least wgt1, and, optionally, wgt2, are specified on the command line with the -w (or --weight or
       --wgt_var ) switch.  If only IR wgt1 is specified then wgt2 is  automatically  computed  as  wgt2=1-wgt1.
       Note that weights larger than 1 are allowed.  Thus it is possible to specify wgt1=2 and wgt2=-3.  One can
       use this functionality to multiply all the values in a given file by a constant.

       The second method of using ncflint is to specify the interpolation option with -i (or with the  --ntp  or
       --interpolate long options). This is really the inverse of the first method in the following sense.  When
       the user specifies the weights directly, ncflint has no work to do besides multiplying the  input  values
       by  their  respective weights and adding the results together to produce the output values.  This assumes
       it is the weights that are known a priori.  In another class of cases it is the  "arrival  value"  (i.e.,
       val3 ) of a particular variable var that is known a priori.  In this case, the implied weights can always
       be inferred by examining the values of var in the input files.  This  results  in  one  equation  in  two
       unknowns, wgt1 and wgt2: val3=wgt1*val1+wgt2*val2.

       Unique  determination  of the weights requires imposing the additional constraint of normalization on the
       weights: wgt1+wgt2=1.  Thus, to use the interpolation option, the user specifies var and val3 with the -i
       option.   ncflint  will  compute  wgt1  and  wgt2, and use these weights on all variables to generate the
       output file.  Although var may have any number of dimensions in the input  files,  it  must  represent  a
       single, scalar value.  Thus any dimensions associated with var must be "degenerate", i.e., of size one.

        If  neither  -i  nor  -w is specified on the command line, ncflint defaults to weighting each input file
       equally in the output file.  This is equivalent to specifying -w0.5 or -w0.5,0.5.  Attempting to  specify
       both .BR -i and -w methods in the same command is an error.

       ncflint  is  programmed  not  to  interpolate  variables  of  type NC_CHAR and NC_BYTE.  This behavior is
       hardcoded.

AUTHOR

       NCO manual pages written by Charlie Zender and originally formatted by Brian Mays.

REPORTING BUGS

       Report bugs to <http://sf.net/bugs/?group_id=3331>.

COPYRIGHT

       Copyright © 1995-2010 Charlie Zender
       This is free software; see the source for copying  conditions.   There  is  NO  warranty;  not  even  for
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO

       The  full  documentation  for NCO is maintained as a Texinfo manual called the NCO User's Guide.  Because
       NCO is mathematical in  nature,  the  documentation  includes  TeX-intensive  portions  not  viewable  on
       character-based displays.  Hence the only complete and authoritative versions of the NCO User's Guide are
       the   PDF   (recommended),    DVI,    and    Postscript    versions    at    <http://nco.sf.net/nco.pdf>,
       <http://nco.sf.net/nco.dvi>,  and  <http://nco.sf.net/nco.ps>,  respectively.   HTML and XML versions are
       available at <http://nco.sf.net/nco.html> and <http://nco.sf.net/nco.xml>, respectively.

       If the info and NCO programs are properly installed at your site, the command

              info nco

       should give you access to the complete manual, except for the TeX-intensive portions.

HOMEPAGE

       The NCO homepage at <http://nco.sf.net> contains more information.

                                                                                                      NCFLINT(1)