Program M3COMBO

Usage

    setenv  <infile>   <path name>
    setenv  <outfile>  <path name>
    setenv COMBO_FILES       <Comma-delimited list of logical names for
                              the input files>
    setenv COMBO_VBLES       <Comma-delimited list of names for
                              the output variables>
    setenv COMBO_UNITS  <units for the output variables>
    For each output variable <name>,
        setenv  <name>_VBLES  <list of input variable names>
        setenv  <name>_FILES  <matching list of input file names>
        setenv  <name>_COEFS  <matching list of REAL coefficients>
        setenv  <name>_OFFSET <matching list of REAL constant terms>
    
    m3combo <and respond to the prompts>

where outfile and the entries in COMBO_FILES are the logical names of the output and input files, respectively. If there is only a single file listed in COMBO_FILES, the <name>_FILES environment variable lists are not needed. The files in the <name>_FILES lists must all occur within the COMBO_FILES list.

NOTE, April 26, 2006

The new multi-file-input version of M3COMBO as of this date is not script compatible with the preceeding version, because of the complexities in specifying linear combinations of variables from multiple input files. The source code for the older (single-input) version is available in file m3combo.0.f for those requiring it; a "saved" copy of the new version is in file m3combo.1.f.

Summary

The M3COMBO program computes linear combinations

Y_i = C_1i V_1i + C_2i V_2i + ... + C_ni V_ni + B_i

of sets of variables { V_ji } using coefficients { C_ji } and constant terms B_i. The program processes a specified time step sequence from a specified set of I/O API files, and writes the output variables Y_i to a different I/O API file, outfile. The input variables must be of basic data type M3REAL; the file type must be one of the following:

Requires Fortran-90 for compilation. Source code for program m3combo is available under the GNU GPL License, Version 2, and can be downloaded here.

Before you run the program, you need to assign logical names to the physical file names of all files, according to Models-3 conventions, using the operation

        "setenv <lname> <pname>"

The program will prompt you for the time step sequence to process , and for the logical name of the output file. The prompts have default responses indicated in square brackets [LIKE THIS], which can be accepted by hitting <RETURN>. The specification of starting date and time, target date and time, and number of time step records for the run follow Models-3 date and time conventions.

If you want to run this program in batch mode (from a script), the recommended way to develop the script is to run the program once interactively noting the pattern of responses to prompts which generate the particular analysis you want. The pattern of responses then becomes either a command-input file which you may redirect into the program in the script, or may become a "here-document" fed into the execution by the script.

Source code for program m3combo is available under the GNU GPL License, Version 2, and can be downloaded here from CMAS or here from GitHub.

See Also:

M3DIFF: compute statistics for pairs of variables and for the results of applying various comparison ("differencing") operations to those variables in a pair of files, with optional I/O API file output of the results.
M3MERGE: merge sets of variables from a set of I/O API input files and write them to an I/O API file.

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