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Arithmetic - arithmetic operations on images and numbers


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


Arithmetic is part of GNU Astronomy Utilities 0.14. 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:

-g, --globalhdu=STR
Use this HDU for all inputs, ignore '--hdu'.
-h, --hdu=STR/INT
Nth call, used for HDU of Nth input FITS.
-w, --wcsfile=STR
File to use for output's WCS.
-W, --wcshdu=STR
HDU/extension to use for output's WCS.
Tessellation (tile grid):
Interpolation metric (radial, manhattan).
-D, --dontdelete
Don't delete output if it exists.
-K, --keepinputdir
Keep input directory for automatic output.
-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.
Table fmt: 'fits-ascii', 'fits-binary', 'txt'.
Operating modes:
-?, --help
give this help list
List all config files and variables read.
BibTeX citation for this program.
Read configuration file STR immediately.
Do not parse any more configuration files.
Information about output(s) in a log file.
Minimum bytes in array to not use ram RAM.
-N, --numthreads=INT
Number of CPU threads to use.
Only run if the program version is STR.
-P, --printparams
Print parameter values to be used and abort.
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.
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:


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Copyright © 2015-2021, 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


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.

January 2021 GNU Astronomy Utilities 0.14