SYNOPSIS

DESCRIPTION

The Normalized Compression Distance between two objects is defined as

NCD(a,b) = (C(a,b) - min(C(a),C(b))) / max(C(a),C(b))

where

C(a,b)

means "the compressed size of the concatenation of a and b"

C(a)

means "the compressed size of a"

C(b)

means "the compressed size of b"
  

ncd will print a non-negative number (typically, but not always, 0 <= x < 1.1) representing how different the two objects are. Smaller numbers represent more similar files. The largest number is somewhere near 1. It is not exactly 1 due to imperfections in compression techniques or other irregularities underlying compressor, but for most standard compression algorithms you are unlikely to see a number above 1.1 in any case.

Three compressors are available by default: bzlib, zlib and blocksort. These may be selected with an option in the complearn.conf, see complearn (5) for more details.

ENUMERATION MODES

-f, --file-mode=FILE

select file mode

-l, --literal-mode=STRING

select string literal mode; this is the default. The next argument is a string which, if containing white space, may be enclosed in double-quotes (")

-p, --plainlist-mode=FILE

select plain list mode; argument is a file which contains a list of files to be individually evaluated

-t, --termlist-mode=FILE

select term list mode; argument is a file which contains string literals to be individually evaluated

-d, --directory-mode=DIR

select directory mode; argument is a path which contains files to be individually evaluated

OPTIONS

-c, --compressor=compressor

use and set compressor to use

-L, --list

list available builtin compressors as well as available compression modules. Modules are loaded from the modules subdirectory of /usr/lib/complearn.

-s, --size

get, in place of NCD, the compressed size of a single FILE, STRING, or DIR

-n, --nexus

Nexus output format for distance matrix

-o, --output=FILE

specify binary output filestem, if different from distmatrix, the default. An extension (.clb, .nex, or .txt) will be added, as appropriate to the output file type.

-b, --binary

output results to binary file; the default name is distmatrix.clb

-q, --quiet

suppress ASCII output and messages

-v, --verbose

activate verbose mode

-h, --help

show help options and exit

FILES

$HOME/.complearn/complearn.conf

/usr/share/complearn/complearn.conf

/usr/local/share/complearn/complearn.conf

 per-user and system configuration files

see complearn(5) for further details.

$HOME/.complearn/modules

/usr/lib/complearn/modules

 standard module automatic loading area.  Any shared object compressor

modules found here will be loaded on startup.

DIAGNOSTICS