%FOPEN  Open file.
%   FID = FOPEN(FILENAME) opens the file FILENAME for read access. FILENAME is the
%   name of the file to be opened.
%
%   FILENAME can be a MATLABPATH relative partial pathname. If the file is not found
%   in the current working directory, FOPEN searches for it on the MATLAB search
%   path. On UNIX systems, FILENAME may also start with a "~/" or a "~username/",
%   which FOPEN expands to the current user's home directory or the specified user's
%   home directory, respectively.
%
%   FID is a scalar MATLAB integer valued double, called a file identifier. You use
%   FID as the first argument to other file input/output routines, such as FREAD and
%   FCLOSE. If FOPEN cannot open the file, it returns -1.
%
%   FID = FOPEN(FILENAME,PERMISSION) opens the file FILENAME in the mode specified by
%   PERMISSION:
%   
%       'r'     open file for reading
%       'w'     open file for writing; discard existing contents
%       'a'     open or create file for writing; append data to end of file
%       'r+'    open (do not create) file for reading and writing
%       'w+'    open or create file for reading and writing; discard existing
%               contents
%       'a+'    open or create file for reading and writing; append data to end of
%               file             
%       'W'     open file for writing without automatic flushing
%       'A'     open file for appending without automatic flushing
%   
%   FILENAME can be a MATLABPATH relative partial pathname only if the file is opened
%   for reading.
%
%   You can open files in binary mode (the default) or in text mode. In binary mode,
%   no characters get singled out for special treatment. In text mode on the PC, the
%   carriage return character preceding a newline character is deleted on input and
%   added before the newline character on output. To open a file in text mode,
%   append 't' to the permission specifier, for example 'rt' and 'w+t'. (On Unix, text and
%   binary mode are the same, so this has no effect. On PC systems this is
%   critical.)
%
%   If the file is opened in update mode ('+'), you must use an FSEEK or FREWIND
%   between an input command like FREAD, FSCANF, FGETS, or FGETL and an output
%   command like FWRITE or FPRINTF. You must also use an FSEEK or FREWIND between an
%   output command and an input command.
%
%   Two file identifiers are automatically available and need not be opened. They
%   are FID=1 (standard output) and FID=2 (standard error).
%   
%   [FID, MESSAGE] = FOPEN(FILENAME,...) returns a system dependent error message if
%   the open is not successful.
%
%   [FID, MESSAGE] = FOPEN(FILENAME,PERMISSION,MACHINEFORMAT) opens the specified
%   file with the specified PERMISSION and treats data read using FREAD or data
%   written using FWRITE as having a format given by MACHINEFORMAT. MACHINEFORMAT is
%   one of the following:
%
%   'native'      or 'n' - local machine format - the default
%   'ieee-le'     or 'l' - IEEE floating point with little-endian byte ordering
%   'ieee-be'     or 'b' - IEEE floating point with big-endian byte ordering
%   'ieee-le.l64' or 'a' - IEEE floating point with little-endian byte ordering and
%                          64 bit long data type
%   'ieee-be.l64' or 's' - IEEE floating point with big-endian byte ordering and 64
%                          bit long data type.
%   
%   [FID, MESSAGE] = FOPEN(FILENAME,PERMISSION,MACHINEFORMAT,ENCODING)
%   opens the specified file using the specified PERMISSION and
%   MACHINEFORMAT. ENCODING specifies the name of a character encoding
%   scheme associated with the file. It must be the empty character vector
%   (''), empty string (""), or a name, or alias for an encoding scheme.
%   Some examples are 'UTF-8', 'latin1', 'US-ASCII', and 'Shift_JIS'. For
%   common names and aliases, see the Web site
%   http://www.iana.org/assignments/character-sets. If ENCODING is
%   unspecified, or is the empty character vector (''), or is the empty
%   string (""), MATLAB's default encoding scheme is used.
%
%   [FILENAME,PERMISSION,MACHINEFORMAT,ENCODING] = FOPEN(FID) returns the filename,
%   permission, machine format, and character encoding values used by MATLAB when it
%   opened the file associated with identifier FID. MATLAB does not determine these
%   output values by reading information from the opened file. For any of these
%   parameters that were not specified when the file was opened, MATLAB returns its
%   default value. The ENCODING is a standard character encoding scheme name that may
%   not be the same as the ENCODING argument used in the call to FOPEN that opened
%   the file. An invalid FID returns empty character vector ('') for all output arguments.
%
%   FIDS = FOPEN('all') returns a row vector containing the file identifiers for all
%   the files currently opened by the user (but not 1 or 2).
%   
%   The 'W' and 'A' permissions do not automatically perform a flush of the current
%   output buffer after output operations.
%   
%   See also FCLOSE, FERROR, FGETL, FGETS, FPRINTF, FREAD, FSCANF, FSEEK, 
%            FTELL, FWRITE.

%   FID = FOPEN(FILENAME) assumes a permission of 'r'.

%   Copyright 1984-2016 The MathWorks, Inc.
%   Built-in function.

