ARITHMETIC(1)

NAME
Arithmetic - arithmetic operations on images and numbers

SYNOPSIS
astarithmetic [OPTION...] ASTRdata or number [ASTRdata] OPERATOR ...

DESCRIPTION
Arithmetic is part of GNU Astronomy Utilities 0.24. Arithmetic will do arithmetic operations on one or multiple images and numbers. Simply put, the name of the image along with the arithmetic operators and possible numbers are given as arguments. The extensions of each input are specified with (possibly multiple) calls to the '--hdu' option.

Currently Arithmetic only supports postfix or reverse polish notation. For example to get the result of '5+6', you should write '5 6 +', or to get the average of two images, you should write 'a.fits b.fits + 2 /' (or more simply use the 'average' operator with 'a.fits b.fits average'). Please see the manual for more information.

Arithmetic recognizes a large collection of standard operators, including basic arithmetic (e.g., +, -, x, /), mathematical (e.g., abs, pow, sqrt, log), statistical (minvalue, min, max, average), comparison (e.g., lt, le, gt), logical (e.g., and, or, not), the full set of bitwise operators, and numeric type conversion operators to all known types. Please run the command below for a complete list describing all operators (press the 'SPACE' keyboard key, or arrow keys, to go down and 'q' to return to the command-line):

    $ info gnuastro "Arithmetic operators"

For more information, please run any of the following commands. In particular the second contains a very comprehensive explanation of Arithmetic's invocation: expected input(s), output(s), and a full description of all the options.

All options and their values:
    $ astarithmetic -P

Inputs/Outputs and options:
    $ info astarithmetic

Full section in manual/book:
    $ info Arithmetic

Full Gnuastro manual/book:
    $ info gnuastro

If you couldn't find your answer in the manual, you can get direct help from experienced Gnuastro users and developers. For more information, please run:

    $ info help-gnuastro

Arithmetic options:

    Input:

--arguments=STR
    Plain-text file with command-line arguments.

--envseed
    Use GSL_RNG_SEED env. for mknoise operator.

-g, --globalhdu=STR
    Use this HDU for all inputs, ignore '--hdu'.

-h, --hdu=STR/INT
    Nth call, used for HDU of Nth input FITS.

-I, --ignorecase
    Ignore case in matching/searching columns.

--searchin=STR
    Select column(s): 'name', 'unit', 'comment'.

-w, --wcsfile=FITS
    File to use for output's WCS.

-W, --wcshdu=STR
    HDU/extension to use for output's WCS.

    Tessellation (tile grid):

--interpmetric=STR
    Interpolation metric (radial, manhattan).

    Output:

--append
    If output file exists, append to existing HDUs.

-a, --writeall
    Write all remaining data in the output.

-c, --metacomment=STR
    Internal comments (FITS images: COMMENT keyword).

-D, --dontdelete
    Don't delete output if it exists.

-K, --keepinputdir
    Keep input directory for automatic output.

-n, --metaname=STR
    Internal name (FITS images: EXTNAME keyword).

--outfitsnocommit
    No Git commit in 0-th HDU of output FITS.

--outfitsnoconfig
    No metadata in 0-th HDU of output FITS.

--outfitsnodate
    No 'DATE' in 0-th HDU of output FITS.

--outfitsnoversions
    No versions in 0-th HDU of output FITS.

-o, --output=STR
    Output file name.

-O, --onedasimage
    Write 1D outputs as an image, not a table.

-s, --onedonstdout
    Write 1D output on stdout, not in a table.

--tableformat=STR
    Table fmt: 'fits-ascii', 'fits-binary', 'txt'.

-u, --metaunit=STR
    Internal units (FITS images: BUNIT keyword).

--wcslinearmatrix=STR
    WCS linear matrix of output ('pc' or 'cd').

    Operating modes:

-?, --help
    give this help list

--checkconfig
    List all config files and variables read.

--cite
    BibTeX citation for this program.

--config=STR
    Read configuration file STR immediately.

--config-prefix=STR
    Custom prefix of option names config files.

--lastconfig
    Do not parse any more configuration files.

--log
    Information about output(s) in a log file.

--minmapsize=INT
    Min. bytes to avoid RAM automatically.

-N, --numthreads=INT
    Number of CPU threads to use.

--onlyversion=STR
    Only run if the program version is STR.

-P, --printparams
    Print parameter values to be used and abort.

--quietmmap
    Don't print mmap'd file's name and size.

-q, --quiet
    Only report errors, remain quiet about steps.

-S, --setdirconf
    Set default values for this directory and abort.

--usage
    give a short usage message

-U, --setusrconf
    Set default values for this user and abort.

-V, --version
    print program version

Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options.

GNU Astronomy Utilities home page: http://www.gnu.org/software/gnuastro/

REPORTING BUGS
Report bugs to bug-gnuastro@gnu.org.

COPYRIGHT
Copyright © 2015-2025 Free Software Foundation, Inc. License GPLv3+: GNU General public license version 3 or later.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

Written/developed by Mohammad Akhlaghi

SEE ALSO
The full documentation for Arithmetic is maintained as a Texinfo manual. If the info and Arithmetic programs are properly installed at your site, the command

    info Arithmetic

should give you access to the complete manual.