# Projects

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The list below summarizes features or bug fixes we would like to see in Octave. if you start working steadily on a project, please let octave-maintainers@octave.org know. We might have information that could help you. You should also read the Contributing Guidelines chapter in the Octave manual.

This list is not exclusive -- there are many other things that might be good projects, but it might instead be something we already have. Also, some of the following items may not actually be considered good ideas now. So please check with octave-maintainers@octave.org before you start working on some large project.

# Numerical

• Improve complex mapper functions. See W. Kahan, ``Branch Cuts for Complex Elementary Functions, or Much Ado About Nothing's Sign Bit (in The State of the Art in Numerical Analysis, eds. Iserles and Powell, Clarendon Press, Oxford, 1987) for explicit trigonometric formulae.
• Make functions like gamma() return the right IEEE Inf or NaN values for extreme args or other undefined cases.
• Improve sqp.
• Fix CollocWt? to handle Laguerre polynomials. Make it easy to extend it to other polynomial types.
• Add optional arguments to colloc so that it's not restricted to Legendre polynomials.
• Fix eig to also be able to solve the generalized eigenvalue problem, and to solve for eigenvalues and eigenvectors without performing a balancing step first.
• Move rand, eye, xpow, xdiv, etc., functions to the matrix classes.
• Use octave_allocator for memory management in Array classes once g++ supports static member templates.
• Improve design of ODE, DAE, classes.
• Make QR more memory efficient for large matrices when not all the columns of Q are required (apparently this is not handled by the lapack code yet).

# GUI/IDE

• Søren Hauberg has suggested that we need C++ code that can:
• Determine if a line of code could be fully parsed, i.e. it would return true for "plot (x, y);", but false for "while (true)".
• Evaluate a line of code and return the output as a string (it would be best if it could provide three strings: output, warnings and errors).
• Query defined variables, i.e. get a list of currently defined variables. Bonus points if it could tell you if anything had changed since the last time you checked the variables (could also be done with signals).
• There is currently a GUI being developed, it's in savannah. Further info can be found here: http://jacobdawid.blogspot.com/2011/08/octave-pure-power.html

# Sparse Matrices

• Improve QR factorization functions, using idea based on CSPARSE cs_dmsol.m
• Improve QR fqctorization by replace CXSPARSE code with SPQR code, and make the linear solve return 2-norm solutions for ill-conditioned matrices based on this new code
• Implement fourth argument to the sprand and sprandn, and addition arguments to sprandsym that the leading brand implements.
• Sparse logical indexing in idx_vector class so that something like 'a=sprandn(1e6,1e6,1e-6); a(a<1) = 0' won't cause a memory overflow.
• Other missing Functions
• symmmd (Superseded by symamd)
• colmmd (Superseded by colamd)
• cholinc
• bicg Moved into octave-core
• gmresMoved into octave-core
• lsqr
• minres
• qmr
• symmlq

# Strings

• Improve performance of string functions, particularly for searching and replacing.
• Make find work for strings.
• Consider making octave_print_internal() print some sort of text representation for unprintable characters instead of sending them directly to the terminal. (But don't do this for fprintf!)
• Consider changing the default value of `string_fill_char' from SPC to NUL.

# Other Data Types

• Template functions for mixed-type ops.
• Convert other functions for use with the floating point type including quad, dasrt, daspk, etc.

# Input/Output

• Make fread and fwrite work for complex data. Iostreams based versions of these functions would also be nice, and if you are working on them, it would be good to support other size specifications (integer*2, etc.).
• Move some pr-output stuff to liboctave.
• Make the cutoff point for changing to packed storage a user-preference variable with default value 8192.
• Complain if there is not enough disk space available (I think there is simply not enough error checking in the code that handles writing data).
• Make it possible to tie arbitrary input and output streams together, similar to the way iostreams can be tied together.

# Interpreter

• Allow customization of the debug prompt.
• Fix the parser so that
```  if (expr) 'this is a string' end
```

is parsed as IF expr STRING END.

• Clean up functions in input.cc that handle user input (there currently seems to be some unnecessary duplication of code and it seems overly complex).
• Consider allowing an arbitrary property list to be attached to any variable. This could be a more general way to handle the help string that can currently be added with `document'.
• Allow more command line options to be accessible as built-in variables (--echo-commands, etc.).
• Make the interpreter run faster.
• Allow arbitrary lower bounds for array indexing.
• Improve performance of recursive function calls.
• Improve the way ignore_function_time_stamp works to allow selecting by individual directories or functions.
• Add a command-line option to tell Octave to just do syntax checking and not execute statements.
• Clean up symtab and variable stuff.
• Input stream class for parser files -- must manage buffers for flex and context for global variable settings.
• make parser do more semantic checking, continue after errors when compiling functions, etc.
• Make LEXICAL_ERROR have a value that is the error message for parse_error() to print?
• Add a run-time alias mechanism that would allow things like alias fun function_with_a_very_long_name so that `function_with_a_very_long_name' could be invoked as `fun'.
• Allow local changes to variables to be written more compactly than is currently possible with unwind_protect. For example,
```      function f ()
local prefer_column_vectors = something;
...
endfunction

```

would be equivalent to

```       function f ()
save_prefer_column_vectors = prefer_column_vectors;
unwind_protect
prefer_column_vectors = something;
...
unwind_protect_cleanup
prefer_column_vectors = save_prefer_column_vectors;
end_unwind_protect
endfunction
```

• Fix all function files to check for bogus inputs (wrong number or types of input arguments, wrong number of output arguments).
• Handle options for built-in functions more consistently.
• Too much time is spent allocating and freeing memory. What can be done to improve performance?
• Error output from Fortran code is ugly. Something should be done to make it look better.
• It would be nice if output from the Fortran routines could be passed through the pager.
• Attempt to recognize common subexpressions in the parser.
• Consider making it possible to specify an empty matrix with a syntax like [](e1, e2). Of course at least one of the expressions must be zero...
• Is Matrix::fortran_vec() really necessary?
• Rewrite whos and the symbol_record_info class. Write a built-in function that gives all the basic information, then write who and whos as M-files.
• On systems that support matherr(), make it possible for users to enable the printing of warning messages.
• Make it possible to mark variables and functions as read-only.
• Make it possible to write a function that gets a reference to a matrix in memory and change one or more elements without generating a second copy of the data.
• Use nanosleep instead of usleep if it is available? Apparently nanosleep is to be preferred over usleep on Solaris systems.
• Start the development of classdef (?)

# Graphics

• Correctly handle case where DISPLAY is unset. Provide --no-window-system or --nodisplay (?) option. Provide --display=DISPLAY option? How will this work with gnuplot (i.e., how do we know whether gnuplot requires an X display to display graphics)?
• Implement transparency and lighting in OpenGL backend(s).

# History

• Add an option to allow saving input from script files in the history list.
• The history command should accept two numeric arguments to indicate a range of history entries to display, save or read.
• Avoid writing the history file if the history list has not changed.
• Avoid permission errors if the history file cannot be opened for writing.
• Fix history problems — core dump if multiple processes are writing to the same history file?

# Configuration and Installation

• Split config.h into a part for Octave-specific configuration things (this part can be installed) and the generic HAVE_X type of configure information that should not be installed.
• Makefile changes:
• eliminate for loops
• define shell commands or eliminate them
• consolidate targets
• Make it possible to configure so that installed binaries and shared libraries are stripped.
• Create a docs-only distribution?
• Better binary packaging and distribution, especially on Windows.
• Octave Emacs mode needs maintenance.

# Documentation and On-Line Help

• Document new features.
• Improve the Texinfo Documentation for the interpreter. It would be useful to have lots more examples, to not have so many forward references, and to not have very many simple lists of functions.
• The docs should mention something about efficiency and that using array operations is almost always a good idea for speed.
• Doxygen documentation for the C++ classes.
• Make index entries more consistent to improve behavior of `help -i'.
• Make `help -i' try to find a whole word match first.
• Clean up help stuff.
• Demo files.
• Document C++ sources, to make it easier for newcomers to get into writing code.
• Flesh out this wiki

# Tests

• Improved set of tests:
• Tests for various functions. Would be nice to have a test file corresponding to every function.
• Tests for element by element operators: + - .* ./ .\ .^ | & < <= == >= > != !
• Tests for boolean operators: && ||
• Tests for other operators: * / \ ' .'
• Tests from bug reports.
• Tests for indexed assignment. Need to consider the following:
• fortran-style indexing
• zero-one indexing
• assignment of empty matrix as well as values resizing
• Tests for all internal functions.

# Programming

• Add support for listeners (addlistener, dellistener, etc) on the C++ side.
• C++ namespace for Octave library functions.
• Better error messages for missing operators?
• Eliminate duplicate enums in pt-exp.cc, pt-const.cc, and ov.cc.
• Handle octave_print_internal() stuff at the liboctave level. Then the octave_value classes could just call on the print() methods for the underlying classes.
• As much as possible, eliminate explicit checks for the types of octave_value objects so that user-defined types will automatically do the right thing in more cases.
• Only include config.h in files that actually need it, instead of including it in every .cc file. Unfortunately, this might not be so easy to figure out.
• GNU coding standards:
• Add a `Makefile' target to the Makefiles.
• Comments on #else and #endif preprocessor commands.
• Change error message format to match standards everywhere.
• Eliminate more global variables.
• Move procstream to liboctave.
• Use references and classes in more places.
• Share more code among the various _options functions.

# Miscellaneous

• Implement some functions for interprocess communication: bind, accept, connect, gethostbyname, etc.
• The installation process should also install octave.el. This needs to detect the appropriate Emacs binary to use to byte-compile the .el file. Following GNU Emacs philosophy, installation would be into \$(prefix)/share/emacs/site-lisp by default, but it should be selectable.
• The ability to transparently handle very large files: Juhana K Kouhia <kouhia@nic.funet.fi> wrote:
If I have a one-dimensional signal data with the size 400 Mbytes, then what are my choices to operate with it:
• I have to split the data
• Octave has a virtual memory on its own and I don't have to worry about the splitting.
If I split the data, then my easily programmed processing programs will become hard to program.
If possible, I would like to have the virtual memory system in Octave i.e., the all big files, the user see as one big array or such. There could be several user selectable models to do the virtual memory depending on what kind of data the user have (1d, 2d) and in what order they are processed (stream or random access).

Perhaps this can be done entirely with a library of M-files.

• An interface to gdb. Michael Smolsky <fnsiguc@weizmann.weizmann.ac.il> wrote:
I was thinking about a tool, which could be very useful for me in my numerical simulation work. It is an interconnection between gdb and octave. We are often managing very large arrays of data in our fortran or c codes, which might be studied with the help of octave at the algorithm development stages. Assume you're coding, say, wave equation. And want to debug the code. It would be great to pick some array from the memory of the code you're developing, fft it and see the image as a log-log plot of the spectral density. I'm facing similar problems now. To avoid high c-development cost, I develop in matlab/octave, and then rewrite into c. It might be so much easier, if I could off-load a c array right from the debugger into octave, study it, and, perhaps, change some [many] values with a convenient matlab/octave syntax, similar to `a(:,50:250)=zeros(100,200)`, and then store it back into the memory of my c code.
• Make the website prettier. Maybe a new design, maybe a more "corporate" design (if we're heading down the "paid support for Octave" path.
• Agora -- website for rapid collaboration related to GNU Octave. Talk to Jordi
• Move Octave-Forge to Savannah so everything is hosted in the same place.

# Performance

• A profiler for Octave would be a very useful tool. And now we have one! But it really needs a better interface.

# Packaging

• create a system that allows packages to deprecate functions as in core. Possibilities are:
• get pkg to accept a deprecated directory inside the package and add it to the search path. Functions in those directories would have to be treated the same as the ones inside the core deprecated
• PKG_ADD can be used to hack this. Package developers would still have to actually write the warnings on the function code but this would allow to have the functions in a separate directory so they don't foget to remove them on the next release
• the package developer can also use something like Make to create a normal package from something that actually had a more complex structure, inclusive deprecated directories
• get pkg to resolve dependencies automatically by downloading and installing them too
• allow to download and install multiple versions of the same package
• make the package just a bit more verbose by default
• make pkg a little more like apt-get
• make pkg support more than one src directory
• now that users can use -forge to automatically install a package without downloading the file themselves they are less likely to read the NEWS of the package. Since pkg now identifies a NEWS file, it couyld offer to show the NEWS file after installing a package

• Squash bugs.