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

• 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

• 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

Summary of changes for version 2.0.6

• 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.