NCFLINT(1)						      General Commands Manual							NCFLINT(1)

NAME

       ncflint - netCDF File Interpolator

SYNTAX

       ncflint	[-3]  [-4]  [-6] [-A] [-C] [-c] [-D dbg] [-d dim,[ min][,[ max]]] [-F] [-h] [-i var,val3][-L dfl_lvl][-l path] [-O] [-p path] [-R]
       [-r] [-t thr_nbr] [-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  nor-
       malized	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 vari-
       able 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 Brian Mays.

REPORTING BUGS

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

COPYRIGHT

       Copyright (C) 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 PARTICU-
       LAR 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)