1NCFLINT(1)                  General Commands Manual                 NCFLINT(1)
2
3
4

NAME

6       ncflint - netCDF File Interpolator
7

SYNTAX

9       ncflint [-3] [-4] [-6] [-A] [-C] [-c] [-D dbg] [-d dim,[ min][,[ max]]]
10       [-F] [-h] [-i var,val3][-L dfl_lvl][-l path] [-O] [-p path]  [-R]  [-r]
11       [-t thr_nbr] [-v var[,...]]  [-w wgt[, wgt2]] [-X box] [-x] file1 file2
12       file3
13

DESCRIPTION

15       ncflint creates an output file that is  a  linear  combination  of  the
16       input files.  This linear combination can be a weighted average, a nor‐
17       malized weighted average, or  an  interpolation  of  the  input  files.
18       Coordinate  variables  are  not acted upon in any case, they are simply
19       copied from file_1.
20        There are two conceptually distinct methods  of  using  ncflint.   The
21       first method is to specify the weight each input file is to have in the
22       output file.  In this method, the value val3 of a variable in the  out‐
23       put  file file_3 is determined from its values val1 and val2 in the two
24       input files according to wgt1*val1+wgt2*val2
25
26       Here at least wgt1, and, optionally, wgt2, are specified on the command
27       line  with  the -w (or --weight or --wgt_var ) switch.  If only IR wgt1
28       is specified then wgt2 is automatically computed as wgt2=1-wgt1.   Note
29       that weights larger than 1 are allowed.  Thus it is possible to specify
30       wgt1=2 and wgt2=-3.  One can use this functionality to multiply all the
31       values in a given file by a constant.
32
33       The  second  method  of  using  ncflint is to specify the interpolation
34       option with -i (or with the --ntp or --interpolate long options).  This
35       is really the inverse of the first method in the following sense.  When
36       the user specifies the weights directly, ncflint  has  no  work  to  do
37       besides  multiplying  the  input values by their respective weights and
38       adding the results together to produce the output values.  This assumes
39       it  is  the weights that are known a priori.  In another class of cases
40       it is the "arrival value" (i.e., val3 ) of a  particular  variable  var
41       that  is  known a priori.  In this case, the implied weights can always
42       be inferred by examining the values of var in the  input  files.   This
43       results   in   one   equation   in   two   unknowns,   wgt1  and  wgt2:
44       val3=wgt1*val1+wgt2*val2.
45
46       Unique determination of the weights requires  imposing  the  additional
47       constraint  of normalization on the weights: wgt1+wgt2=1.  Thus, to use
48       the interpolation option, the user specifies var and val3 with  the  -i
49       option.   ncflint  will compute wgt1 and wgt2, and use these weights on
50       all variables to generate the output file.  Although var may  have  any
51       number  of  dimensions  in the input files, it must represent a single,
52       scalar value.  Thus any dimensions associated with var must be  "degen‐
53       erate", i.e., of size one.
54
55        If  neither  -i  nor  -w  is  specified  on  the command line, ncflint
56       defaults to weighting each input file equally in the output file.  This
57       is  equivalent to specifying -w0.5 or -w0.5,0.5.  Attempting to specify
58       both .BR -i and -w methods in the same command is an error.
59
60       ncflint is programmed not to interpolate variables of type NC_CHAR  and
61       NC_BYTE.  This behavior is hardcoded.
62
63

AUTHOR

65       NCO manual pages written by Charlie Zender and Brian Mays.
66
67

REPORTING BUGS

69       Report bugs to <http://sf.net/bugs/?group_id=3331>.
70
71

73       Copyright © 1995-2010 Charlie Zender
74       This is free software; see the source for copying conditions.  There is
75       NO warranty; not even for MERCHANTABILITY or FITNESS FOR  A  PARTICULAR
76       PURPOSE.
77
78

SEE ALSO

80       The full documentation for NCO is maintained as a Texinfo manual called
81       the NCO User's Guide.  Because NCO is mathematical in nature, the docu‐
82       mentation  includes  TeX-intensive  portions not viewable on character-
83       based displays.  Hence the only complete and authoritative versions  of
84       the  NCO  User's  Guide  are the PDF (recommended), DVI, and Postscript
85       versions at  <http://nco.sf.net/nco.pdf>,  <http://nco.sf.net/nco.dvi>,
86       and  <http://nco.sf.net/nco.ps>,  respectively.   HTML and XML versions
87       are      available      at       <http://nco.sf.net/nco.html>       and
88       <http://nco.sf.net/nco.xml>, respectively.
89
90       If  the  info and NCO programs are properly installed at your site, the
91       command
92
93              info nco
94
95       should give you access to the complete  manual,  except  for  the  TeX-
96       intensive portions.
97
98

HOMEPAGE

100       The NCO homepage at <http://nco.sf.net> contains more information.
101
102
103
104                                                                    NCFLINT(1)
Impressum