# News for Octave Version 2

## Summary of changes for version 2.0.10

- The built-in variable `PWD' has been removed. If you need to get the value of the current working directory, use the pwd() function instead.

- For compatibility with Matlab, Octave's lyap function now solves

            A*X + X*A' + C = 0

  instead of

            A'*X + X*A + C = 0

  To try to avoid confusion for people who are used to the way Octave behaved in previous versions, a warning is printed the first time lyap is called in a given session. To completely disable the warning, simply add

            global __disable_lyap_interface_change_warning__;

  to your ~/.octaverc file. The warning will eventually disappear for good in some future version of Octave.

- New built-in functions for computing Bessel functions: besseli, besselj, besselk, and bessely.

- The gammai and betai functions are now implemented as built-in functions rather than function files.

- The new built-in variable `implicit_num_to_str_ok' controls whether Octave converts expressions like `[97, 98, 99, "123"]' to strings. The default value is 0 unless you use --traditional.

- The new built-in variable `fixed_point_format' controls whether Octave uses a scaled fixed-point format for displaying matrices. The default value is 0 unless you use --traditional.

- The function sumsq now computes sum (x .* conj (x)) for complex values.

- Dynamically linked functions can be cleared.

- If a .oct file has a time stamp more recent than the time that it was loaded, it is automatically reloaded. Reloading a .oct file may cause several functions to be cleared automatically. By default, a warning is printed that lists the names of the functions that will be cleared. You can suppress the message by setting the new built-in variable `warn_reload_forces_clear' to 0.

- Global variables are now initialized to the empty matrix, for compatibility with Matlab.

- Explicit initialization of global variables only happens once. For example, after the following statements are evaluated, g still has the value 1.

            global g = 1
            global g = 2

  This is useful for initializing global variables that are used to maintain state information that is shared among several functions.

- The new built-in variable max_recursion_depth allows you to prevent Octave from attempting infinite recursion. The default value is 256.

- Octave now uses readline version 2.1 and kpathsea 3.0.

- The libreadline and libkpathsea libraries are no longer installed.

- The libcruft, liboctave, and liboctinterp libraries are now installed in $libdir/octave instead of just $libdir.

- It's no longer necessary to have libg++, but you do need to have the GNU implementation of libstdc++. If you are using gcc 2.7.2, libstdc++ is distributed as part of libg++ 2.7.2. For later versions, libstdc++ is distributed separately. For egcs, libstdc++ is included with the compiler distribution.

## Summary of changes for version 2.0.9

This is a bug-fixing release, but there is one new user-visible feature:

- It is now possible to specify a label for lines in the plot key when using the plot function. For example,

            plot (x, y, "-*;sin(x);")

  plots y vs. x using the linespoints style and sets the title of the line in the key to be `sin(x)'

## Summary of changes for version 2.0.8

This is a bug-fixing release. There are only a few new user-visible features.

- If the argument to eig() is symmetric, Octave uses the specialized Lapack subroutine for symmetric matrices for a significant increase in performance.

- It is now possible to use the mkoctfile script to create .oct files from multiple source and object files.

## Summary of changes for version 2.0.7

This is a bug-fixing release. There are no new user-visible features.

## Summary of changes for version 2.0.6

This is primarily a bug-fixing release. There are only a few new user-visilbe features.

- The new built-in variable default_eval_print_flag controls whether Octave prints the results of commands executed by eval() that do not end with semicolons. The default is 1.

- The new built-in constant OCTAVE_HOME specifies the top-level directory where Octave is installed.

- Octave no longer includes functions to work with NPSOL or QPSOL, because they are not free software.

## Summary of changes for version 2.0.5

- A `switch' statement is now available. See the Statements chapter in the manual for details.

- Commands like ls, save, and cd may now also be used as formal parameters for functions.

- More tests.

## Summary of changes for version 2.0.4

- It is now possible to use commands like ls, save, and cd as simple variable names. They still cannot be used as formal parameters for functions, or as the names of structure variables. Failed assignments leave them undefined (you can recover the orginal function definition using clear).

- Is is now possible to invoke commands like ls, save, and cd as normal functions (for example, load ("foo", "x", "y", "z")).

## Summary of changes for version 2.0.3

- The manual has been completely revised and now corresponds much more closely to the features of the current version.

- The return value for assignment expressions is now the RHS since that is more consistent with the way other programming languages work. However, Octave still prints the entire LHS value so that

            x = zeros (1, 2);
            x(2) = 1

  still prints

            x =

              0  1

  but an assignment like

            z = x(2) = 1

  sets z to 1 (not [ 0, 1 ] as in previous versions of Octave).

- It is now much easier to make binary distributions. See the Binary Distributions section of the manual for more details.

## Summary of changes for version 2.0.2

- Octave now stops executing commands from a script file if an error is encountered.

- The return, and break commands now cause Octave to quit executing commands from script files. When used in invalid contexts, the break, continue, and return commands are now simply ignored instead of producing parse errors.

- size ("") is now [0, 0].

- New functions:
  sleep
    pause execution for a specified number of seconds
  usleep
    pause execution for a specified number of microseconds

## Summary of changes for version 2.0.1

Other than bug fixes, there were no user-visible changes in version 2.0.1.

## Summary of changes for version 2.0

- The set and show commands for setting and displaying gnuplot parameters have been replaced by gset and gshow. This change will probably break lots of things, but it is necessary to allow for compatibility with the Matlab graphics and GUI commands in a future version of Octave. (For now, the old set and show commands do work, but they print an annoying warning message to try to get people to switch to using gset.)

- Octave has been mostly ported to Windows NT and Windows 95 using the beta 17 release of the Cygnus GNU-WIN32 tools. Not everything works, but it is usable. See the file README.WINDOWS for more information.

- Dynamic linking works on more systems using dlopen() and friends (most modern Unix systems) or shl_load() and friends (HP/UX systems). A simple example is provided in examples/hello.cc. For this feature to work, you must configure Octave with --enable-shared. You may also need to have a shared-library version of libg++ and libstdc++.

- New data types can be added to Octave by writing a C++ class. On systems that support dynamic linking, new data types can be added to an already running Octave binary. A simple example appears in the file examples/make_int.cc. Other examples are the standard Octave data types defined in the files src/ov*.{h,cc} and src/op-*.cc.

- The configure option --enable-bounds-check turns on bounds checking on element references for Octave's internal array and matrix classes. It's enabled by default. To disable this feature, configure Octave with --disable-bounds-check.

- The C-style I/O functions (fopen, fprintf, etc.) have been rewritten to be more compatible with Matlab. The fputs function has also been added. Usage of the *printf functions that was allowed in previous versions of Octave should still work. However, there is no way to make the new versions of the *scanf functions compatible with Matlab *and* previous versions of Octave. An optional argument to the *scanf functions is now available to make them behave in a way that is compatible with previous versions of Octave.

- Octave can now read files that contain columns of numbers only, with no header information. The name of the loaded variable is constructed from the file name. Each line in the file must have the same number of elements.

- The interface to the pager has changed. The new built-in variable `page_output_immediately' controls when Octave sends output to the pager. If it is nonzero, Octave sends output to the pager as soon as it is available. Otherwise, Octave buffers its output and waits until just before the prompt is printed to flush it to the pager.

- Expressions of the form

            A(i,j) = x

  where X is a scalar and the indices i and j define a matrix of elements now work as you would expect rather than giving an error. I am told that this is how Matlab 5.0 will behave when it is released.

- Indexing of character strings now works.

- The echo command has been implemented.

- The document command is now a regular function.

- New method for handling errors:

            try
              BODY
            catch
              CLEANUP
            end_try_catch

  Where BODY and CLEANUP are both optional and may contain any Octave expressions or commands. The statements in CLEANUP are only executed if an error occurs in BODY.

  No warnings or error messages are printed while BODY is executing. If an error does occur during the execution of BODY, CLEANUP can access the text of the message that would have been printed in the builtin constant __error_text__. This is the same as eval (TRY, CATCH) (which may now also use __error_text__) but it is more efficient since the commands do not need to be parsed each time the TRY and CATCH statements are evaluated.

- Octave no longer parses the help command by grabbing everything after the keyword `help' until a newline character is read. To get help for `;' or `,', now, you need to use the command `help semicolon' or `help comma'.

- Octave's parser now does some simple constant folding. This means that expressions like 3*i are now evaluated only once, when a function is compiled, and the right hand side of expressions like a = [1,2;3,4] are treated as true matrix constants rather than lists of elements which must be evaluated each time they are needed.

- Built-in variables that can take values of "true" and "false" can now also be set to any nonzero scalar value to indicate "true", and 0 to indicate "false".

- New built-in variables `history_file', `history_size', and `saving_history'.

- New built-in variable `string_fill_char' specifies the character to fill with when creating arrays of strings.

- If the new built-in variable `gnuplot_has_frames' is nonzero, Octave assumes that your copy of gnuplot includes support for multiple plot windows when using X11. If the new built-in variable `gnuplot_has_multiplot' is nonzero, Octave assumes that your copy of gnuplot has the multiplot support that is included in recent 3.6beta releases. The initial values of these variables are determined by configure, but can be changed in your startup script or at the command line in case configure got it wrong, or if you upgrade your gnuplot installation.

- The new plot function `figure' allows multiple plot windows when using newer versions of gnuplot with X11.

- Octave now notices when the plotter has exited unexpectedly.

- New built-in variable `warn_missing_semicolon'. If nonzero, Octave will warn when statements in function definitions don't end in semicolons. The default value is 0.

- Octave now attempts to continue after floating point exceptions or out-of-memory errors.

- If Octave crashes, it now attempts to save all user-defined variables in a file named `octave-core' in the current directory before exiting.

- It is now possible to get the values of individual option settings for the dassl, fsolve, lsode, npsol, qpsol, and quad functions using commands like

            dassl_reltol = dassl_options ("relative tolerance");

- The svd() function no longer computes the left and right singular matrices unnecessarily. This can significantly improve performance for large matrices if you are just looking for the singular values.

- The filter() function is now a built-in function.

- New function randn() returns a pseudo-random number from a normal distribution. The rand() and randn() functions have separate seeds and generators.

- Octave's command-line arguments are now available in the built-in variable `argv'. The program name is also available in the variables `program_invocation_name' and `program_name'. If executing a script from the command line (e.g., octave foo.m) or using the `#! /bin/octave' hack, the program name is set to the name of the script.

- New built-in variable `completion_append_char' used as the character to append to successful command-line completion attempts. The default is " " (a single space).

- Octave now uses a modified copy of the readline library from version 1.14.5 of GNU bash.

- In prompt strings, `\H' expands to the whole host name.

- New built-in variable `beep_on_error'. If nonzero, Octave will try to ring your terminal's bell before printing an error message. The default value is 0.

- For functions defined from files, the type command now prints the text of the file. You can still get the text reconstructed from the parse tree by using the new option -t (-transformed).

- New command-line argument --traditional sets the following preference variables for compatibility with Matlab:

            PS1                           = ">> "
            PS2                           = ""
            beep_on_error                 = 1
            default_save_format           = "mat-binary"
            define_all_return_values      = 1
            do_fortran_indexing           = 1
            empty_list_elements_ok        = 1
            implicit_str_to_num_ok        = 1
            ok_to_lose_imaginary_part     = 1
            page_screen_output            = 0
            prefer_column_vectors         = 0
            prefer_zero_one_indexing      = 1
            print_empty_dimensions        = 0
            treat_neg_dim_as_zero         = 1
            warn_function_name_clash      = 0
            whitespace_in_literal_matrix  = "traditional"

- New functions:
  readdir
    returns names of files in directory as array of strings
  mkdir
    create a directory
  rmdir
    remove a directory
  rename
    rename a file
  unlink
    delete a file
  umask
    set permission mask for file creation
  stat
    get information about a file
  lstat
    get information about a symbolic link
  glob
    perform filename globbing
  fnmatch
    match strings with filename globbing patterns
  more
    turn the pager on or off
  gammaln
    alias for lgamma

- New audio functions from Andreas Weingessel:
  lin2mu
    linear to mu-law encoding
  loadaudio
    load an audio file to a vector
  mu2lin
    mu-law to linear encoding
  playaudio
    play an audio file
  record
    record sound and store in vector
  saveaudio
    save a vector as an audio file
  setaudio
    executes mixer shell command

- New plotting functions from Vinayak Dutt. Ones dealing with multiple plots on one page require features from gnuplot 3.6beta (or later).
  bottom_title
    put title at the bottom of the plot
  mplot
    multiplot version of plot
  multiplot
    switch multiple-plot mode on or off
  oneplot
    return to one plot per page
  plot_border
    put a border around plots
  subplot
    position multiple plots on a single page
  subwindow
    set subwindow position for next plot
  top_title
    put title at the top of the plot
  zlabel
    put a label on the z-axis

- New string functions
  bin2dec
    convert a string of ones and zeros to an integer
  blanks
    create a string of blanks
  deblank
    delete trailing blanks
  dec2bin
    convert an integer to a string of ones and zeros
  dec2hex
    convert an integer to a hexadecimal string
  findstr
    locate occurrences of one string in another
  hex2dec
    convert a hexadecimal string to an integer
  index
    return position of first occurrence a string in another
  rindex
    return position of last occurrence a string in another
  split
    divide one string into pieces separated by another
  str2mat
    create a string matrix from a list of strings
  strrep
    replace substrings in a string
  substr
    extract a substring

  The following functions return a matrix of ones and zeros. Elements that are nonzero indicate that the condition was true for the corresponding character in the string array.

  isalnum
    letter or a digit
  isalpha
    letter
  isascii
    ascii
  iscntrl
    control character
  isdigit
    digit
  isgraph
    printable (but not space character)
  islower
    lower case
  isprint
    printable (including space character)
  ispunct
    punctuation
  isspace
    whitespace
  isupper
    upper case
  isxdigit
    hexadecimal digit

  These functions return new strings.

  tolower
    convert to lower case
  toupper
    convert to upper case

- New function, fgetl. Both fgetl and fgets accept an optional second argument that specifies a maximum number of characters to read, and the function fgets is now compatible with Matlab.

- Printing in hexadecimal format now works (format hex). It is also possible to print the internal bit representation of a value (format bit). Note that these formats are only implemented for numeric values.

- Additional structure features:
  - Name completion now works for structures.
  - Values and names of structure elements are now printed by default. The new built-in variable `struct_levels_to_print' controls the depth of nested structures to print. The default value is 2.
  - New functions:
    struct_contains (S, NAME)
      returns 1 if S is a structure with element NAME; otherwise returns 0.
    struct_elements (S)
      returns the names of all elements of structure S in an array of strings.

- New io/subprocess functions:
  fputs
    write a string to a file with no formatting
  popen2
    start a subprocess with 2-way communication
  mkfifo
    create a FIFO special file
  popen
    open a pipe to a subprocess
  pclose
    close a pipe from a subprocess
  waitpid
    check the status of or wait for subprocesses

- New time functions:
  asctime
    format time structure according to local format
  ctime
    equivalent to `asctime (localtime (TMSTRUCT))'
  gmtime
    return time structure corresponding to UTC
  localtime
    return time structure corresponding to local time zone
  strftime
    print given time structure using specified format
  time
    return current time

  The `clock' and `date' functions are now implemented in M-files using these basic functions.

- Access to additional Unix system calls:
  dup2
    duplicate a file descriptor
  exec
    replace current process with a new process
  fcntl
    control open file descriptors
  fork
    create a copy of the current process
  getpgrp
    return the process group id of the current process
  getpid
    return the process id of the current process
  getppid
    return the process id of the parent process
  getuid
    return the real user id of the current process
  getgid
    return the real group id of the current process
  geteuid
    return the effective user id of the current process
  getegid
    return the effective group id of the current process
  pipe
    create an interprocess channel

- Other new functions:
  commutation_matrix
    compute special matrix form
  duplication_matrix
    compute special matrix form
  common_size.m
    bring arguments to a common size
  completion_matches
    perform command completion on string
  tilde_expand
    perform tilde expansion on string
  meshgrid
    compatible with Matlab's meshgrid function
  tmpnam
    replaces octave_tmp_file_name
  atexit
    register functions to be called when Octave exits
  putenv
    define an environment variable
  bincoeff
    compute binomial coefficients
  nextpow2
    compute the next power of 2 greater than a number
  detrend
    remove a best fit polynomial from data
  erfinv
    inverse error function
  shift
    perform a circular shift on the elements of a matrix
  pow2
    compute 2 .^ x
  log2
    compute base 2 logarithms
  diff
    compute differences of matrix elements
  vech
    stack columns of a matrix below the diagonal
  vec
    stack columns of a matrix to form a vector
  xor
    compute exclusive or

- Functions for getting info from the password database on Unix systems:
  getpwent
    read entry from password-file stream, opening if necessary
  getpwuid
    search for password entry with matching user ID
  getpwnam
    search for password entry with matching username
  setpwent
    rewind the password-file stream
  endpwent
    close the password-file stream

- Functions for getting info from the group database on Unix systems:
  getgrent
    read entry from group-file stream, opening if necessary
  getgrgid
    search for group entry with matching group ID
  getgrnam
    search for group entry with matching group name
  setgrent
    rewind the pgroup-file stream
  endgrent
    close the group-file stream

- The New function octave_config_info returns a structure containing information about how Octave was configured and compiled.

- New function getrusage returns a structure containing system resource usage statistics. The `cputime' function is now defined in an M-file using getrusage.

- The info reader is now a separate binary that runs as a subprocess. You still need the info reader distributed with Octave though, because there are some new command-line arguments that are not yet available in the public release of Info.

- There is a new built-in variable, INFO_PROGRAM, which is used as the name of the info program to run. Its initial value is $OCTAVE_HOME/lib/octave/VERSION/exec/ARCH/info, but that value can be overridden by the environment variable OCTAVE_INFO_PROGRAM, or the command line argument --info-program NAME, or by setting the value of INFO_PROGRAM in a startup script.

- There is a new built-in variable, EXEC_PATH, which is used as the list of directories to search when executing subprograms. Its initial value is taken from the environment variable OCTAVE_EXEC_PATH (if it exists) or PATH, but that value can be overridden by the the command line argument --exec-path PATH, or by setting the value of EXEC_PATH in a startup script. If the EXEC_PATH begins (ends) with a colon, the directories $OCTAVE_HOME/lib/octave/VERSION/exec/ARCH and $OCTAVE_HOME/bin are prepended (appended) to EXEC_PATH (if you don't specify a value for EXEC_PATH explicitly, these special directories are prepended to your PATH).

- If it is present, Octave will now use an `ls-R' database file to speed up recursive path searching. Octave looks for a file called ls-R in the directory specified by the environment variable OCTAVE_DB_DIR. If that is not set but the environment variable OCTAVE_HOME is set, Octave looks in $OCTAVE_HOME/lib/octave. Otherwise, Octave looks in the directory $datadir/octave (normally /usr/local/lib/octave).

- New examples directory.

- There is a new script, mkoctfile, that can be used to create .oct files suitable for dynamic linking.

- Many more bug fixes.

- ChangeLogs are now kept in each subdirectory.