GNU Octave Version 1
Summary of important uservisible changes
News for version 6 5 4.4 4.2 4 3.8 3.6 3.4 3.2 3 2 1 (Release History)
 Summary of important uservisible changes
 Version 1.1.1
 Version 1.1.0
 Version 1.0
 Version 0.83
 Version 0.82
 Version 0.81
 Version 0.80
 Version 0.79
 Version 0.78
 Version 0.77
 Version 0.76
 Version 0.75
 Version 0.74
 Version 0.73
 Version 0.72
 Version 0.71
 Version 0.70
 Version 0.69
 Version 0.68
 Version 0.67
 Version 0.66
 Version 0.63
 Version 0.61
 Version 0.57
 Version 0.56
 Version 0.55
 Version 0.52
 Version 0.51
 Version 0.50
Version 1.1.1
* New builtin variables, default_return_value and define_all_return_values. If define_all_return_values is set to "false", Octave does not do anything special for return values that are left undefined, and you will get an error message if you try to use them. For example, if the function function [x, y] = f () y = 1; endfunction is called as octave:13> [a, b] = f () Octave will print an error message for the attempt to assign an undefined value to `a'. This is incompatible with Matlab, which will define the return variable `x' to be the empty matrix. To get the Matlablike behavior, you can set the variable define_all_return_values to "true" (the default is "false") and default_return_value to `[]' (the default). Then, any return values that remain undefined when the function returns will be initialized to `[]'. If the function is called without explicitly asking for an output, it will succeed. This behavior is compatible and unchanged from previous versions of Octave. * New builtin variable suppress_verbose_help_message. If set to "true", Octave will not add additional help information to the end of the output from the help command and usage messages for builtin commands. The default value is "false". * New builtin variable PS4 is used as the prefix of echoed input (enabled with the echoinput (x) option). * The function size() now accepts an optional second argument. * Output from `save  ...' now goes through the pager. * The break statement may also be used to exit a function, for compatibility with Matlab. * The directory tree for installing Octave is now closer to conforming with the current GNU standards. * More bug fixes.
Version 1.1.0
* Octave now requires g++ 2.6.3 or later. This change is necessary to make template instantiations cleaner, and to avoid having to have special cases in the code for earlier versions of gcc. * A new data structure type has been added. The implementation uses an associative array with indices limited to strings, but the syntax is more like Cstyle structures. here are some examples of using it. Elements of structures can be of any type, including structures: octave:1> x.a = 1; octave:2> x.b = [1, 2; 3, 4]; octave:3> x.c = "string"; octave:4> x x = <structure: a b c> octave:5> x.a x.a = 1 octave:6> x.b x.b = 1 2 3 4 octave:7> x.c x.c = string octave:8> x.b.d = 3 x.b.d = 3 octave:9> x.b x.b = <structure: d> octave:10> x.b.d x.b.d = 3 Functions can return structures: octave:1> a = rand (3) + rand (3) * I; octave:2> function y = f (x) > y.re = real (x); > y.im = imag (x); > endfunction octave:3> f (a) ans = <structure: im re> octave:4> ans.im ans.im = 0.093411 0.229690 0.627585 0.415128 0.221706 0.850341 0.894990 0.343265 0.384018 octave:5> ans.re ans.re = 0.56234 0.14797 0.26416 0.72120 0.62691 0.20910 0.89211 0.25175 0.21081 Return lists can include structure elements: octave:1> [x.u, x.s, x.v] = svd ([1, 2; 3, 4]) x.u = 0.40455 0.91451 0.91451 0.40455 x.s = 5.46499 0.00000 0.00000 0.36597 x.v = 0.57605 0.81742 0.81742 0.57605 octave:8> x x = <structure: s u v> This feature should be considered experimental, but it seems to work ok. Suggestions for ways to improve it are welcome. * Octave now supports a limited form of exception handling modelled after the unwindprotect form of Lisp: unwind_protect BODY unwind_protect_cleanup CLEANUP end_unwind_protect Where BODY and CLEANUP are both optional and may contain any Octave expressions or commands. The statements in CLEANUP are guaranteed to be executed regardless of how control exits BODY. This is useful to protect temporary changes to global variables from possible errors. For example, the following code will always restore the original value of the builtin variable do_fortran_indexing even if an error occurs while performing the indexing operation. save_do_fortran_indexing = do_fortran_indexing; unwind_protect do_fortran_indexing = "true"; elt = a (idx) unwind_protect_cleanup do_fortran_indexing = save_do_fortran_indexing; end_unwind_protect Without unwind_protect, the value of do_fortran_indexing would not be restored if an error occurs while performing the indexing operation because evaluation would stop at the point of the error and the statement to restore the value would not be executed. * Recursive directory searching has been implemented using Karl Berry's kpathsea library. Directories below path elements that end in // are searched recursively for .m files. * Octave now waits for additional input when a pair of parentheses is `open' instead of giving an error. This allows one to write statements like this if (big_long_variable_name == other_long_variable_name  not_so_short_variable_name > 4 && y > x) some (code, here); without having to clutter up the if statement with continuation characters. * Continuation lines are now allowed in string constants and are handled correctly inside matrix constants. * Both `...{whitespace}\n' and `\{whitespace}\n' can be used to introduce continuation lines, where {whitespace} may include spaces, tabs and comemnts. * The script directory has been split up by topic. * Dynamic linking mostly works with dld. The following limitations are known problems:  Clearing dynamically linked functions doesn't work.  Dynamic linking only works with dld, which has not been ported to very many systems yet.  Configuring with enablelitekernel seems to mostly work to make nonessential builtin functions dynamically loaded, but there also seem to be some problems. For example, fsolve seems to always return info == 3. This is difficult to debug since gdb won't seem to allow breakpoints to be set inside dynamically loaded functions.  Octave uses a lot of memory if the dynamically linked functions are compiled with g. This appears to be a limitation with dld, and can be avoided by not using g to compile functions that will be linked dynamically. * fft2 and ifft2 are now builtin functions. * The `&&' and `' logical operators are now evaluated in a shortcircuit fashion and work differently than the element by element operators `&' and `'. See the Octave manual for more details. * Expressions like 1./m are now parsed as 1 ./ m, not 1. / m. * The replot command now takes the same arguments as gplot or gsplot (except ranges, which cannot be respecified with replot (yet)) so you can add additional lines to existing plots. * The hold command has been implemented. * New function `clearplot' clears the plot window. The name `clg' is aliased to `clearplot' for compatibility with Matlab. * The commands `gplot clear' and `gsplot clear' are equivalent to `clearplot'. (Previously, `gplot clear' would evaluate `clear' as an ordinary expression and clear all the visible variables.) * The Matlabstyle plotting commands have been improved. They now accept linestyle arguments, multiple xy pairs, and other plot option flags. For example, plot (x, y, "@12", x, y2, x, y3, "4", x, y4, "+") results in a plot with y plotted with points of type 2 ("+") and color 1 (red). y2 plotted with lines. y3 plotted with lines of color 4. y4 plotted with points which are "+"s. the help message for `plot' and `plot_opt' provide full descriptions of the options. * NaN is now dropped from plot data, and Inf is converted to a very large value before calling gnuplot. * Improved load and save commands:  The save and load commands can now read and write a new binary file format. Conversion to and from IEEE big and little endian formats is handled automatically. Conversion for other formats has not yet been implemented.  The load command can now read Matlab .mat files, though it is not yet able to read sparse matrices or handle conversion for all data formats.  The save command can write Matlab .mat files.  The load command automatically determines the save format (binary, ascii, or Matlab binary).  The default format for the save command is taken from the builtin variable `default_save_format'.  The save and load commands now both accept a list of globbing patterns so you can easily load a list of variables from a file.  The load command now accepts the option list, for listing the variable names without actually loading the data. With verbose, it prints a long listing.  The load command now accepts the option floatbinary, for saving floating point data in binary files in single precision. * who and whos now accept a list of globbing patterns so you can limit the lists of variables and functions to those that match a given set of patterns. * New functions for manipulating polynomials compan  companion matrix corresponding to polynomial coefficients conv  convolve two vectors deconv  deconvolve two vectors roots  find the roots of a polynomial poly  characteristic polynomial of a matrix polyderiv  differentiate a polynomial polyinteg  integrate a polynomial polyreduce  reduce a polynomial to minimum number of terms polyval  evaluate a polynomial at a point polyvalm  evaluate a polynomial in the matrix sense residue  partial fraction expansion corresponding to the ratio of two polynomials * New functions for manipulating sets create_set  create a set of unique values complement  find the complement of two sets intersection  find the intersection of two sets union  find the union of two sets * New elementary functions: acot acoth acsc acsch asec asech cot coth csc csch log2 sec sech * New special functions: beta  beta function betai  incomplete beta function gammai  incomplete gamma function * New image processing functions: colormap  set and return current colormap gray  set a gray colormap gray2ind  image format conversion image  display an image imagesc  scale and display an image imshow  display images ind2gray  image format conversion ind2rgb  image format conversion loadimage  load an image from a file ntsc2rgb  image format conversion ocean  set a color colormap rgb2ind  image format conversion rgb2ntsc  image format conversion saveimage  save an image to a file * New time and date funcitons: tic  set wallclock timer toc  get elapsed wallclock time, since timer last set etime  another way to get elapsed wallclock time cputime  get CPU time used since Octave started is_leap_year  is the given year a leap year? * Other new functions: bug_report  submit a bug report to the bugoctave mailing list toascii  convert a string to a matrix of ASCII character codes octave_tmp_file  generate a unique temporary file name undo_string_escapes  replace special characters in a string by their backslash forms is_struct  determine whether something is a structure data type feof  check EOF condition for a specified file ferror  check error state for a specified file fread  read binary data from a file fwrite  write binary data to a file file_in_path  check to see if named file exists in given path kbhit  get a single character from the terminal axis  change plot ranges hist  plot histograms diary  save commands and output to a file type  show the definition of a function which  print the type of an identifier or the location of a function file isieee  Returns 1 if host uses IEEE floating point realmax  Returns largest floating point number realmin  Returns smallest floating point number gcd  greatest common divisor lcm  least common multiple null  orthonormal basis of the null space of a matrix orth  orthonormal basis of the range space of a matrix fft2  twodimensional fast fourier transform ifft2  twodimensional inverse fast fourier transform filter  digital filter fftfilt  filter using fft fftconv  convolve to vectors using fft sinc  returns sin(pi*x)/(pi*x) freqz  compute the frequency response of a filter * The meaning of nargin (== args.length ()) in builtin functions has been changed to match the meaning of nargin in userdefined functions. * Variable return lists. Octave now has a real mechanism for handling functions that return an unspecified number of values, so it is no longer necessary to place an upper bound on the number of outputs that a function can produce. Here is an example of a function that uses the new syntax to produce n values: function [...] = foo (n) for i = 1:n vr_val (i * x); endfor endfunction * New keyword, all_va_args, that allows the entire list of va_args to be passed to another function. For example, given the functions function f (...) while (nargin) disp (va_arg ()) endwhile endfunction function g (...) f ("begin", all_va_args, "end") endfunction the statement g (1, 2, 3) prints begin 1 2 3 end all_va_args may be used more than once, but can only be used within functions that take a variable number of arguments. * If given a second argument, svd now returns an economysized decomposition, eliminating the unecessary rows or columns of U or V. * The max and min functions correctly handle complex matrices in which some columns contain real values only. * The find function now handles 2 and 3 output arguments. * The qr function now allows computation of QR with pivoting. * hilb() is much faster for large matrices. * computer() is now a builtin function. * pinv() is now a builtin function. * The output from the history command now goes through the pager. * If a function is called without assigning the result, nargout is now correctly set to 0. * It is now possible to write functions that only set some return values. For example, calling the function function [x, y, z] = f () x = 1; z = 2; endfunction as [a, b, c] = f () produces: a = 1 b = [](0x0) c = 2 * The shell_cmd function has been renamed to system (the name shell_cmd remains for compatibility). It now returns [output, status]. * New builtin variable `OCTAVE_VERSION'. Also a new function, version, for compatibility with Matlab. * New builtin variable `automatic_replot'. If it is "true", Octave will automatically send a replot command to gnuplot each time the plot changes. Since this is fairly inefficient, the default value is "false". * New builtin variable `whitespace_in_literal_matrix' allows some control over how Octave decides to convert spaces to commas in matrix expressions like `[m (1)]'. If the value of `whitespace_in_literal_matrix' is "ignore", Octave will never insert a comma or a semicolon in a literal matrix list. For example, the expression `[1 2]' will result in an error instead of being treated the same as `[1, 2]', and the expression [ 1, 2, 3, 4 ] will result in the vector [1 2 3 4] instead of a matrix. If the value of `whitespace_in_literal_matrix' is "traditional", Octave will convert spaces to a comma between identifiers and `('. For example, given the matrix m = [3 2] the expression [m (1)] will be parsed as [m, (1)] and will result in [3 2 1] and the expression [ 1, 2, 3, 4 ] will result in a matrix because the newline character is converted to a semicolon (row separator) even though there is a comma at the end of the first line (trailing commas or semicolons are ignored). This is apparently how Matlab behaves. Any other value for `whitespace_in_literal_matrix' results in behavior that is the same as traditional, except that Octave does not convert spaces to a comma between identifiers and `('. For example, the expression [m (1)] will produce 3. This is the way Octave has always behaved. * Line numbers in error messages for functions defined in files and for script files now correspond to the file line number, not the number of lines after the function keyword appeared. * Octave now extracts help from script files. The comments must come before any other statements in the file. * In function files, the first block of comments in the file will now be interpreted as the help text if it doesn't look like the Octave copyright notice. Otherwise, Octave extracts the first set of comments after the function keyword. * The function clock is more accurate on systems that have the gettimeofday() function. * The standard output stream is now automatically flushed before reading from stdin with any of the *scanf() functions. * Expanded reference card. * The Octave distribution now includes a frequently asked questions file, with answers. Better answers and more questions (with answers!) are welcome. * New option verbose. If Octave is invoked with verbose and not silent, a message is printed if an octaverc file is read while Octave is starting. * An improved configure script generated by Autoconf 2.0. * Lots of bug fixes.
Version 1.0
 Cstyle I/O functions now handle files referenced by name or by number more consistently.
Version 0.83

Loading global symbols should work now.

Clearing the screen doesn’t reprint the prompt unnecessarily.

The operations
<complex scalar> OP <real matrix>
forOP == +, , *, or ./
no longer crash Octave. 
More portability and configuration fixes.
Version 0.82
* Octave now comes with a reference card. * The manual has been improved, but more work remains to be done. * The atanh function now works for complex arguments. * The asin, acos, acosh, and atanh functions now work properly when given realvalued arguments that produce complex results. * SEEK_SET, SEEK_CUR, and SEEK_END are now constants. * The `using' qualifier now works with gplot and gsplot when the data to plot is coming directly from a file. * The strcmp function now works correctly for empty strings. * Eliminated bogus parse error for Mfiles that don't end with `end' or `endfunction'. * For empty matrices with one nonzero dimension, the +, , .*, and ./ operators now correctly preserve the dimension. * Octave no longer crashes if you type ^D at the beginning of a line in the middle of defining a loop or if statement. * On AIX systems, Back off on indexing DiagArray via Proxy class to avoid gcc (or possibly AIX assembler?) bug. * Various other bug and portability fixes.
Version 0.81
* Octave no longer dumps core if you try to define a function in your .octaverc file. * Fixed bug in Array class that resulted in bogus offdiagonal elements when computing eigenvalue and singular value decompositions. * Fixed bug that prevented lsode from working on the SPARCstation, at least with some versions of Sun's f77. This bug was introduced in 0.80, when I changed LSODE to allow the user to abort the integration from within the RHS function. * Fixed bug that prevented global attribute of variables from being saved with save(), and another that prevented load() from working at all.
Version 0.80
* I have started working on a manual for the C++ classes. At this point, it is little more than a list of function names. If you would like to volunteer to help work on this, please contact bugoctave@bevo.che.wisc.edu. * The patterns accepted by the save and clear commands now work like file name globbing patterns instead of regular expressions. I apologize for any inconvenience this change may cause, but file name globbing seems like a more reasonable style of pattern matching for this purpose. * It is now possible to specify tolerances and other optional inputs for dassl, fsolve, lsode, npsol, qpsol, and quad. For each of these functions, there is a corresponding function X_options, which takes a keyword and value arguments. If invoked without any arguments, the X_options functions print a list of possible keywords and current values. For example, npsol_options () prints a list of possible options with values, and npsol_options ("major print level", 10) sets the major print level to 10. The keyword match is not case sensitive, and the keywords may be abbreviated to the shortest unique match. For example, npsol_options ("ma p", 10) is equivalent to the statement shown above. * The new builtin variable save_precision can be used to set the number of digits preserved by the ASCII save command. * Assignment of [] now works in most cases to allow you to delete rows or columns of matrices and vectors. For example, given a 4x5 matrix A, the assignment A (3, :) = [] deletes the third row of A, and the assignment A (:, 1:2:5) = [] deletes the first, third, and fifth columns. * Variable argument lists. Octave now has a real mechanism for handling functions that take an unspecified number of arguments, so it is no longer necessary to place an upper bound on the number of optional arguments that a function can accept. Here is an example of a function that uses the new syntax to print a header followed by an unspecified number of values: function foo (heading, ...) disp (heading); va_start (); while (nargin) disp (va_arg ()); endwhile endfunction Note that the argument list must contain at least one named argument (this restriction may eventually be removed), and the ellipsis must appear as the last element of the argument list. Calling va_start() positions an internal pointer to the first unnamed argument and allows you to cycle through the arguments more than once. It is not necessary to call va_start() if you do not plan to cycle through the arguments more than once. * Recursive functions should work now. * The environment variable OCTAVE_PATH is now handled in the same way as TeX handles TEXINPUTS. If the path starts with `:', the standard path is prepended to the value obtained from the environment. If it ends with `:' the standard path is appended to the value obtained from the environment. * New functions, from Kurt Hornik (hornik@neuro.tuwien.ac.at) and the Department of Probability Theory and Statistics TU Wien, Austria: corrcoef  corrcoef (X, Y) is the correlation between the ith variable in X and the jth variable in Y corrcoef (X) is corrcoef (X, X) cov  cov (X, Y) is the covariance between the ith variable in X and the jth variable in Y cov (X) is cov (X, X) gls  generalized least squares estimation kurtosis  kurtosis(x) = N^(1) std(x)^(4) SUM_i (x(i)mean(x))^4  3 If x is a matrix, return the row vector containing the kurtosis of each column mahalanobis  returns Mahalanobis' Dsquare distance between the multivariate samples X and Y, which must have the same number of components (columns), but may have a different number of observations (rows) ols  ordinary least squares estimation pinv  returns the pseudoinverse of X; singular values less than tol are ignored skewness  skewness (x) = N^(1) std(x)^(3) SUM_i (x(i)mean(x))^3 if x is a matrix, return the row vector containing the skewness of each column * Errors in usersupplied functions called from dassl, fsolve, lsode, npsol, and quad are handled more gracefully. * Programming errors in the use of the C++ classes within Octave should no longer cause Octave to abort. Instead, Octave's error handler function is called and execution continues as best as is possible. This should result in eventually returning control to the toplevel Octave prompt. (It would be nice to have a real exception handling mechanism...) * A number of memory leaks have been eliminated. Thanks to Fong Kin Fui <fui@ee.nus.sg> for reporting them. * The C++ matrix classes are now derived from a generic templatebased array class. * The readline function operateandgetnext (from bash) is now available and bound to CO by default. * Octave now uses the version of readline currently distributed with bash1.13. On some systems, interactive invocations of Octave will now blink the cursor to show matching parens. * By default, include files are now installed in $prefix/include/octave instead of $prefix/include. * Octave now uses a config.h file instead of putting all defines on the compiler command line.
Version 0.79
* New control systems functions: dgram  Returns the discrete controllability and observability gramian. dlqr  Discrete linear quadratic regulator design. dlqe  Discrete linear quadratic estimator (Kalman Filter) design. c2d  Convert continuous system description to discrete time description assuming zeroorder hold and given sample time. * The max (min) functions can now return the index of the max (min) value as a second return value.
Version 0.78
* Octave's handling of global variables has been completely rewritten. To access global variables inside a function, you must now declare them to be global within the function body. Likewise, if you do not declare a variable as global at the command line, you will not have access to it within a function, even if it is declared global there. For example, given the function function f () global x = 1; y = 2; endfunction the global variable `x' is not visible at the top level until the command octave:13> global x has been evaluated, and the variable `y' remains local to the function f() even if it is declared global at the top level. Clearing a global variable at the top level will remove its global scope and leave it undefined. For example, octave:1> function f () # Define a function that accesses > global x; # the global variable `x'. > x > endfunction octave:2> global x = 1 # Give the variable `x' a value. octave:3> f () # Evaluating the function accesses the x = 1 # global `x'. octave:4> clear x # Remove `x' from global scope, clear value. octave:5> x = 2 # Define new local `x' at the top level x = 2 octave:6> f # The global `x' is no longer defined. error: `x' undefined near line 1 column 25 error: evaluating expression near line 1, column 25 error: called from `f' octave:7> x # But the local one is. x = 2 * The new function, `is_global (string)' returns 1 if the variable named by string is globally visible. Otherwise, returns 0. * The implementation of `who' has changed. It now accepts the following options: b builtins  display info for builtin variables and functions f functions  display info for currently compiled functions v variables  display info for user variables l long  display long info The long output looks like this: octave:5> who l *** currently compiled functions: prot type rows cols name ==== ==== ==== ==== ==== wd user function   f *** local user variables: prot type rows cols name ==== ==== ==== ==== ==== wd real scalar 1 1 y *** globally visible user variables: prot type rows cols name ==== ==== ==== ==== ==== wd complex matrix 13 13 x where the first character of the `protection' field is `w' if the symbol can be redefined, and `' if it has readonly access. The second character may be `d' if the symbol can be deleted, or `' if the symbol cannot be cleared. * The new builtin variable ignore_function_time_stamp can be used to prevent Octave from calling stat() each time it looks up functions defined in Mfiles. If set to "system", Octave will not automatically recompile Mfiles in subdirectories of $OCTAVE_HOME/lib/VERSION if they have changed since they were last compiled, but will recompile other Mfiles in the LOADPATH if they change. If set to "all", Octave will not recompile any Mfiles unless their definitions are removed with clear. For any other value of ignore_function_time_stamp, Octave will always check to see if functions defined in Mfiles need to recompiled. The default value of ignore_function_time_stamp is "system". * The new builtin variable EDITOR can be used to specify the editor for the edit_history command. It is set to the value of the environment variable EDITOR, or `vi' if EDITOR is not set, or is empty. * There is a new builtin variable, INFO_FILE, which is used as the location of the info file. Its initial value is $OCTAVE_HOME/info/octave.info, so `help i' should now work provided that OCTAVE_HOME is set correctly, even if Octave is installed in a directory different from that specified at compile time. * There is a new command line option, infofile FILE, that may be used to set Octave's idea of the location of the info file. It will override any value of OCTAVE_INFO_FILE found in the environment, but not any INFO_FILE="filename" commands found in the system or user startup files. * Octave's Info reader will now recognize gzipped files that have names ending in `.gz'. * The save command now accepts regular expressions as arguments. Note that these patterns are regular expressions, and do not work like filename globbing. For example, given the variables `a', `aa', and `a1', the command `save a*' saves `a' and `aa' but not `a1'. To match all variables beginning with `a', you must use an expression like `a.*' (match all sequences beginning with `a' followed by zero or more characters). * Line and column information is included in more error messages.
Version 0.77
* Improved help. The command `help i topic' now uses the GNU Info browser to display help for the given topic directly from the Texinfo documenation. * New function: chol  Cholesky factorization.
Version 0.76
* Better runtime error messages. Many now include line and column information indicating where the error occurred. Octave will also print a traceback for errors occurring inside functions. If you find error messages that could use improvement, or errors that Octave fails to catch, please send a bug report to bugoctave@bevo.che.wisc.edu. * If gplot (or gsplot) is given a string to plot, and the string does not name a file, Octave will pass the string along to gnuplot directly. This allows commands like gplot "sin (x)" w l, data w p to work (assuming that data is a variable containing a matrix of values). * Long options (help, version, etc.) are supported.
Version 0.75
* The documentation is much more complete, but still could use a lot of work. * The history function now prints line numbers by default. The command `history q' will omit them. * The clear function now accepts regular expressions. * If gplot (or gsplot) is given a string to plot, and the string names a file, Octave attempts to plot the contents of the file. * New functions: history: run_history  run commands from the history list. edit_history  edit commands from the history list with your favorite editor. linear algebra: balance  Balancing for algebraic and generalized eigenvalue problems. givens  Givens rotation. is_square  Check to see if a matrix is square. qzhess  QZ decomposition of the matrix pencil (a  lambda b). qzval  Generalized eigenvalues for real matrices. syl  Sylvester equation solver. control systems: is_symmetric  Check to see if a matrix is symmetric. abcddim  Check dimensions of linear dynamic system [A,B,C,D]. is_controllable  Check to see if [A,B,C,D] is controllable. is_observable  Check to see if [A,B,C,D] is observable. are  Solve algebraic Ricatti equation. dare  Solve discretetime algebraic Ricatti equation. lqe  Kalman filter design for continuous linear system. lqr  Linear Quadratic Regulator design. lyap  Solve Lyapunov equation. dlyap  Solve discrete Lyapunov equation. tzero  Compute the transmission zeros of [A,B,C,D].
Version 0.74
* Formal parameters to functions are now always considered to be local variables, so things like global x = 0 global y = 0 function y = f (x) x = 1; y = x; end f (x) result in the function returning 1, with the global values of x and y unchanged. * Multiple assignment expressions are now allowed to take indices, so things like octave:13> [a([1,2],[3,4]), b([5,6],[7,8])] = lu ([1,2;3,4]) will work correctly.
Version 0.73
* Saving and loading global variables works correctly now. * The save command no longer saves builtin variables. * Global variables are more reliable. * Matrices may now have one or both dimensions zero, so that operations on empty matrices are now handled more consistently. By default, dimensions of the empty matrix are now printed along with the empty matrix symbol, `[]'. For example: octave:13> zeros (3, 0) ans = [](3x0) The new variable `print_empty_dimensions' controls this behavior. See also Carl de Boor, An Empty Exercise, SIGNUM, Volume 25, pages 26, 1990, or C. N. Nett and W. M. Haddad, A SystemTheoretic Appropriate Realization of the Empty Matrix Concept, IEEE Transactions on Automatic Control, Volume 38, Number 5, May 1993. * The right and left division operators `/' and `\' will now find a minimum norm solution if the system is not square, or if the coefficient matrix is singular. * New functions: hess  Hessenberg decomposition schur  Ordered Schur factorization perror  print error messages corresponding to error codes returned from the functions fsolve, npsol, and qpsol (with others to possibly be added later). * Octave now prints a warning if it finds anything other than whitespace or comments after the final `end` or `endfunction` statement. * The bodies of functions, and the for, while, and if commands are now allowed to be empty. * Support for Gill and Murray's QPSOL has been added. Like NPSOL, QPSOL is not freely redistributable either, so you must obtain your own copy to be able to use this feature. More information about where to find QPSOL and NPSOL are in the file README.NLP.
Version 0.72
* For numeric output, columns are now lined up on the decimal point. (This requires libg++2.3.1 or later to work correctly). * If octave is running interactively and the output intended for the screen is longer than one page and a pager is available, it is sent to the pager through a pipe. You may specify the program to use as the pager by setting the variable PAGER. PAGER may also specify a command pipeline. * Spaces are not always significant inside square brackets now, so commands like [ linspace (1, 2) ] will work. However, some possible sources of confusion remain because Octave tries (possibly too hard) to determine exactly what operation is intended from the context surrounding an operator. For example:  In the command [ 1  1 ] the `' is treated as a binary operator and the result is the scalar 0, but in the command [ 1 1 ] the `' is treated as a unary operator and the result is the vector [ 1 1 ].  In the command a = 1; [ 1 a' ] the single quote character `'' is treated as a transpose operator and the result is the vector [ 1 1 ], but in the command a = 1; [ 1 a ' ] an error message indicating an unterminated string constant is printed. * Assignments are just expressions now, so they are valid anywhere other expressions are. This means that things like if (a = n < m) ... endif are valid. This is parsed as: compare `n < m', assign the result to the variable `a', and use it as the test expression in the if statement. To help avoid errors where `=' has been used but `==' was intended, Octave issues a warning suggesting parenthesis around assignments used as truth values. You can suppress this warning by adding parenthesis, or by setting the value of the new builtin variable `warn_assign_as_truth_value' to 'false' (the default value is 'true'). This is also true for multiple assignments, so expressions like [a, b, c] = [u, s, v] = expression are now possible. If the expression is a function, nargout is set to the number of arguments for the rightmost assignment. The other assignments need not contain the same number of elements. Extra left hand side variables in an assignment become undefined. * The default line style for plots is now `lines' instead of `points'. To change it, use the `set data style STYLE' command. * New file handling and I/O functions: fopen  open a file for reading or writing fclose  close a file fflush  flush output to a file fgets  read characters from a file frewind  set file position to the beginning of a file fseek  set file position ftell  tell file position freport  print a report for all open files fscanf  read from a file sscanf  read from a string scanf  read from the standard input * New builtin variables for file and I/O functions: stdin  file number corresponding to the standard input stream. stdout  file number corresponding to the standard output stream. stderr  file number corresponding to the standard error stream. The following may be used as the final (optional) argument for fseek: SEEK_SET  set position relative to the beginning of the file. SEEK_CUR  set position relative to the current position. SEEK_END  set position relative to the end of the file. * New function: setstr  convert vectors or scalars to strings (doesn't work for matrices yet). * If possible, computer now prints the system type instead of always printing `Hi Dave, I'm a HAL9000'. * Octave now properly saves and restores its internal state correctly in more places. Interrupting Octave while it is executing a script file no longer causes it to exit. * Octave now does tilde expansion on each element of the LOADPATH. * A number of memory leaks have been plugged. * Dependencies for C++ source files are now generated automatically by g++. * There is a new command line option, p PATH, that may be used to set Octave's loadpath from the command line. It will override any value of OCTAVE_PATH found in the environment, but not any LOADPATH="path" commands found in the system or user startup files. * It is now possible to override Octave's default idea of the location of the systemwide startup file (usually stored in $(prefix)/lib/octave/octaverc) using the environment variable OCTAVE_HOME. If OCTAVE_HOME has a value, Octave will look for octaverc and its Mfiles in the directory $OCTAVE_HOME/lib/octave. This allows people who are using binary distributions (as is common with systems like Linux) to install the real octave binary in any directory (using a name like octave.bin) and then install a simple script like this #!/bin/sh OCTAVE_HOME=/foo/bar/baz export OCTAVE_HOME exec octave.bin to be invoked as octave.
Version 0.71
* Much improved plotting facility. With this release, Octave does not require a specially modified version of gnuplot, so gnuplot sources are no longer distributed with Octave. For a more detailed description of the new plotting features, see the file PLOTTING. * New plotting commands: plot  2D plots semilogx  2D semilog plot with logscale on the x axis semilogy  2D semilog plot with logscale on the y axis loglog  2D loglog plot mesh  3D mesh plot meshdom  create matrices for 3D plotting from two vectors contour  contour plots of 3D data bar  create bar graphs stairs  create stairstep plots polar  2D plots from thetaR data grid  turn plot grid lines on or off xlabel, ylabel  place labels on the x and y axes of 2D plots sombrero  demonstrate 3D plotting gplot  2D plot command with gnuplotlike syntax gsplot  3D plot command with gnuplotlike syntax set  set plot options with gnuplot syntax show  show plot options with gnuplot syntax closeplot  close stream to gnuplot process purge_tmp_files  delete temporary files created by plot command * Other new commands: ls, dir  print a directory listing shell_cmd  execute shell commands keyboard  get input from keyboard, useful for debugging menu  display a menu of options and ask for input fft  fast fourier transform ifft  inverse fast fourier transform * Strings may be enclosed in either single or double quote characters. Double quote characters are not special within single quote strings, and single quotes are not special within double quote strings. * Command name completion now works for Mfile names too. * Better help and usage messages for many functions. * Help is now available for functions defined in Mfiles. The first block of comments is taken as the text of the help message. * Numerous changes in preparation to support dynamic loading of object files with dld. * Bug fixes to make solving DAEs with dassl actually work. * The command `save file' now saves all variables in the named file. * If do_fortran_indexing is 'true', indexing a scalar with [1,1,1,...] (n times) replicates its value n times. The orientation of the resulting vector depends on the value of prefer_column_vectors. * Things like [[1,2][3,4]] no longer cause core dumps, and invalid input like [1,2;3,4,[5,6]] now produces a diagnositic message. * The cd, save, and load commands now do tilde expansion. * It's now possible to clear global variables and functions by name. * Use of clear inside functions is now a parse error.
Version 0.70
* Better parse error diagnostics. For interactive input, you get messages like octave:1> a = 3 + * 4; parse error: a = 3 + * 4; ^ and for script files, the message includes the file name and input line number: octave:1> foo parse error near line 4 of file foo.m: a = 3 + * 4; ^ * New builtin variable PS2 which is used as the secondary prompt. The default value is '> '. * New file, octavemode.el, for editing Octave code with GNU Emacs. This is a modified version of Matthew R. Wette's matlabmode.el. * Better support for missing math functions. * User preferences are now cached in a global struct so we don't have to do a symbol table lookup each time we need to know what they are. This should mean slightly improved performance for evaluating expressions.
Version 0.69
* Multiple assignments are now possible, so statements like a = b = c = 3; a = b = c = [1,2;3,4]; or c = (a = (b = 2) * 3 + 4) * 5 are legal, as are things that have even more bizarre effects, like a(4:6,4:6) = b(2:3,2:3) = [1,2;3,4]; (try it). * Improved parsing of strings (but they still don't work as matrix elements). * An Mfile may now either define a function or be a list of commands to execute. * Better detection and conditional compilation of IEEE functions isinf, finite, and isnan. * Replacements for acosh, asinh, atanh, and gamma from the BSD math library for those systems that don't have them.
Version 0.68
* New functions: eval  evaluate a string as a sequence of Octave commands. input  print a prompt and get user input.
Version 0.67
* New functions: find  return the indices of nonzero elements. * Zeroone style indexing now works. For example, a = [1,2,3,4]; b = a([1,0,0,1]) sets b to the first and fourth elememnts of a. Zeroone style indexing also works for indexing the left hand side of an assignment. For example, a = rand (1,2;3,4); a([0,1],:) = [1,2] sets the second row of a to [1 2] The behavior for the ambiguous case a = [1,2,3,4]; b = a([1,1,1,1]); is controlled by the new global variable `prefer_zero_one_indexing'. If this variable is equal to 'true', b will be set to [1 2 3 4]. If it is false, b will be set to [1 1 1 1]. The default value is 'false'. * Using the new global variable `propagate_empty_matrices', it is possible to have unary andy binary operations on empty matrices return an empty matrix. The default value of this variable is 'warn', so that empty matrices are propagated but you get a warning. Some functions, like eig and svd have also been changed to handle this. * Empty matrices can be used in conditionals, but they always evaluate to `false'. With propagate_empty_matrices = 'true', both of the following expressions print 0: if [], 1, else 0, end if ~[], 1, else 0, end * Octave no longer converts input like `3.2 i' or `3 I' to complex constants directly because that causes problems inside square brackets, where spaces are important. This abbreviated notation *does* work if there isn't a space between the number and the i, I, j, or J.
Version 0.66
* Logical unary not operator (~ or !) now works for complex. * Left division works. * Right and left element by element division should work correctly now. * Numbers like .3e+2 are no longer errors. * Indexing a matrix with a complex value doesn't cause a core dump. * The min and max functions should work correctly for two arguments. * Improved (I hope!) configuration checks. * Octave is now installed as octaveM.N, where M and N are version numbers, and octave is a link to that file. This makes it possible to have more than one version of the interpreter installed.
Version 0.63
* The reshape function works again. * Octave now converts input like `3.2i' or `3 I' or `2.3e5 j' to be complex constants directly, rather than requiring an expression like `3.3 * i' to be evaluated.
Version 0.61
* Octave has been successfully compiled using gcc 2.3.3 and libg++ 2.3. on a 486 system running Linux. * The win_texas_lotto function is now called texas_lotto (it's a script file, and win_texas_lotto.m is too long for some Linux and System V systems).
Version 0.57
* The Clike formatted print functions printf, fprintf, and sprintf finally work.
Version 0.56
* By default, octave prints a short disclaimer when it starts. (You can suppress it by invoking octave with q). * You can keep octave from reading your ~/.octaverc and .octaverc files by invoking it with f. * When returning two values, eig now returns [v, d] instead of [lambda, v], where d is a diagonal matrix made from lambda. * The win_texas_lotto function now produces a sorted list. * New functions: expm  matrix exponential. logm  matrix logarithm.
Version 0.55
* The following (Cstyle) backslash escape sequences work in quoted strings (useful(?) with printf()): \a bell \r carriage return \b backspace \t horizontal tab \f formfeed \v vertical tab \n newline \\ backslash * Use of `...' at the end of a line will allow a statement to continue over more than one line. * The names `inf' and `nan' are now aliases for `Inf' and `NaN', respectively. * New functions: casesen  print a warning if the luser tries to turn off case sensitivity. median  find median value. norm  compute the norm of a matrix. sort  sort columns. * New variable, `silent_functions'. If silent_functions == 'true', the results of expressions are not printed even if they are not followed by a semicolon. The disp() and printf() functions still result in output. The default value for this variable is 'false'. * New variable `return_last_value_computed'. If it is 'true', functions defined in script files return the last value computed if a return value has not been explicitly declared. The default value for this variable is 'false'.
Version 0.52
* Name completion works for function and variable names currently in the symbol tables. Coming soon: completion for names of functions defined in script files but not yet compiled. * The initial value of do_fortran_indexing is now false, and the initial value of prefer_column_vectors is now true. Swap the values of these variables if you want behavior that is more like Matlab. * All script files check the number of input arguments before doing much real work. * The identifiers `i' and `j' are now also names for sqrt(1). These symbols may be used for other purposes, but their original definition will reappear if they are cleared. * The symbol tables are now implemented with hash tables for faster searching. * A small amount of help is now available for most builtin operators, keywords and functions. Coming soon: help for script files. * Without any arguments, the help command now lists all known builtin operators, keywords and functions. * Generic parse errors are now signalled by `Eh, what's up doc?', which is closer to what Bugs actually says. * The who command now only prints variable names by default. Use the fcn (or fcns, or functions) switch to print the names of builtin or currently compiled functions.
Version 0.51

Major overhaul of array indexing.

The colloc function actually works now.
Version 0.50
* The lsode and dassl functions now return the states only, instead of the time and the states, so you must keep track of the corresponding times (this is easy though, because you have to specify a vector of desired output times anyway). * Solution of NLPs with NPSOL now works on the SPARC. * New keywords `endif', `endfor', `endfunction', `endif', and `endwhile', which allow for better diagnostics. The `end' keyword is still recognized. All script files have been changed to use these new keywords in place of `end'. * It is now possible to uninstall Octave by doing a `make uninstall' in the top level directory. * The Makefiles are much closer to conforming with GNU coding standards. * New functions: win_texas_lotto  produce six unique random numbers between 1 and 50. quad  numerical integration. lu  LU factorization qr  QR factorization dassl  Solution of DAEs using DASSL. * New files: THANKS  A list of people and organazations who have supported the development of Octave. NEWS  This file, listing recent changes. * Help is now available at the gnuplot prompt.