STYLE(1)

NAME
style - analyse surface characteristics of a document

SYNOPSIS
style [-L language] [-l length] [-r ari] [file...]
style [--language language] [--print-long length] [--print-ari ari] [file...]
style -h|--help
style --version

DESCRIPTION
Style analyses the surface characteristics of the writing style of a document. It prints various readability grades, length of words, sentences and paragraphs. It can further locate sentences with certain characteristics. If no files are given, the document is read from standard input.

Numbers are counted as words with one syllable. A sentence is a sequence of words, that starts with a capitalised word and ends with a full stop, double colon, question mark or exclaimation mark. A single letter followed by a dot is considered an abbreviation, so it does not end a sentence. Various multi-letter abbreviations are recognized, they do not end a sentence as well. A paragraph consists of two or more new line characters.

Style understands cpp(1) #line lines for being able to give precise locations when printing sentences.

  Kincaid Formula
The Kincaid Formula has been developed for Navy training manuals, that ranged in difficulty from 5.5 to 16.3. It is probably best applied to technical documents, because it is based on adult training manuals rather than school book text. Dialogs (often found in fictional texts) are usually a series of short sentences, which lowers the score. On the other hand, scientific texts with many long scientific terms are rated higher, although they are not neccessarily harder to read for people who are familar with those terms.

Kincaid = 11.8*syllables/wds+0.39*wds/sentences-15.59

  Automated Readability Index
The Automated Readability Index is typically higher than Kincaid and Coleman-Liau, but lower than Flesch.

ARI = 4.71*chars/wds+0.5*wds/sentences-21.43

  Coleman-Liau Formula
The Coleman-Liau Formula usually gives a lower grade than Kincaid, ARI and Flesch when applied to technical documents.

Coleman-Liau = 5.89*chars/wds-0.3*sentences/(100*wds)-15.8

  Flesh reading easy formula
The Flesh reading easy formula has been developed by Flesh in 1948 and it is based on school text covering grade 3 to 12. It is wide spread, especially in the USA, because of good results and simple computation. The index is usually between 0 (hard) and 100 (easy), standard English documents averages approximately 60 to 70. Applying it to German documents does not deliver good results because of the different language structure.

Flesch Index = 206.835-84.6*syll/wds-1.015*wds/sent

  Fog Index
The Fog index has been developed by Robert Gunning. Its value is a school grade. The ``ideal'' Fog Index level is 7 or 8. A level above 12 indicates the writing sample is too hard for most people to read. Only use it on texts of at least hundred words to get meaningful results.

Fog Index = 0.4*(wds/sent+100*((wds >= 3 syll)/wds))

  WSTF Index
The first new Vienna text formula (1. neue Wiener Sachtextformel, WSTF) has been developed for German documents and its result is a school grade that could read the text.

WSTF Index = 0.1935*(wds >= 3 syllables)/wds
             +0.1672*wds/sent
             -0.1297*(wds > 6 characters)/wds
             -0.0327*(wds = 1 syllable)/wds
             -0.875

  Wheeler-Smith Index
The Wheeler-Smith Index is mapped to school grades using a table:

Wheeler-Smith Index = wds/sent*(wds >= 3 syll)/wds/10

    Index | 16 |  | 20 |  | 24 |  | 29 |  | 34 |  | 38 |  | 42
    School year |  | 5 |  | 6 |  | 7 |  | 8 |  | 9 |  | 10

  Lix formula
The Lix formula developed by Björnsson from Sweden is very simple and employs a mapping table as well:

Lix = wds/sent+(wds >= 6 char)/wds

    Index | 34 |  | 38 |  | 41 |  | 44 |  | 48 |  | 51 |  | 54 |  | 57
    School year |  | 5 |  | 6 |  | 7 |  | 8 |  | 9 |  | 10 |  | 11

  SMOG-Grading
The SMOG-Grading for English texts has been developed by McLaughlin in 1969. Its result is a school grade.

SMOG-Grading = square root of ((wds >= 3 syll)*sent/30) + 3

It has been adapted to German by Bamberger & Vanecek in 1984, who changed the constant +3 to -2.

OPTIONS

-L language, --language language
    set the document language.

-l length, --print-long length
    print all sentences longer than length words.

-r ari, --print-ari ari
    print all sentences whose readability index (ARI) is greater than ari.

-h, --help
    Print a short usage message.

--version
    Print the version.

ERRORS
On usage errors, 1 is returned. Termination caused by lack of memory is signalled by exit code 2.

ENVIRONMENT

LC_MESSAGES=de|en
    specifies the default document language. The default language is en.

LC_CTYPE=iso-8859-1
    specifies the document character set. The default character set is ASCII.

AUTHOR
This program is GNU software, copyright 1997, 1998 Michael Haardt (michael@cantor.informatik.rwth-aachen.de).

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

HISTORY
There has been a style command on old UNIX systems, which is now part of the AT&T DWB package. The original version was bound to roff by enforcing a call to deroff.

SEE ALSO
deroff(1), diction(1)

Cherry, L.L.; Vesterman, W.: Writing Tools—The STYLE and DICTION programs, Computer Science Technical Report 91, Bell Laboratories, Murray Hill, N.J. (1981), republished as part of the 4.4BSD User's Supplementary Documents by O'Reilly.