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This is Info file octave, produced by Makeinfo-1.64 from the input file octave.tex. START-INFO-DIR-ENTRY * Octave: (octave). Interactive language for numerical computations. END-INFO-DIR-ENTRY Copyright (C) 1996, 1997 John W. Eaton. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions. File: octave, Node: Controlling Subprocesses, Next: Process ID Information, Prev: Filesystem Utilities, Up: System Utilities Controlling Subprocesses ======================== Octave includes some high-level commands like `system' and `popen' for starting subprocesses. If you want to run another program to perform some task and then look at its output, you will probably want to use these functions. Octave also provides several very low-level Unix-like functions which can also be used for starting subprocesses, but you should probably only use them if you can't find any way to do what you need with the higher-level functions. - Built-in Function: system (STRING, RETURN_OUTPUT, TYPE) Execute a shell command specified by STRING. The second argument is optional. If TYPE is `"async"', the process is started in the background and the process id of the child process is returned immediately. Otherwise, the process is started, and Octave waits until it exits. If TYPE argument is omitted, a value of `"sync"' is assumed. If two input arguments are given (the actual value of RETURN_OUTPUT is irrelevant) and the subprocess is started synchronously, or if SYSTEM is called with one input argument and one or more output arguments, the output from the command is returned. Otherwise, if the subprocess is executed synchronously, it's output is sent to the standard output. To send the output of a command executed with SYSTEM through the pager, use a command like disp (system (cmd, 1)); or printf ("%s\n", system (cmd, 1)); The `system' function can return two values. The first is any output from the command that was written to the standard output stream, and the second is the output status of the command. For example, [output, status] = system ("echo foo; exit 2"); will set the variable `output' to the string `foo', and the variable `status' to the integer `2'. - Built-in Function: fid = popen (COMMAND, MODE) Start a process and create a pipe. The name of the command to run is given by COMMAND. The file identifier corresponding to the input or output stream of the process is returned in FID. The argument MODE may be `"r"' The pipe will be connected to the standard output of the process, and open for reading. `"w"' The pipe will be connected to the standard input of the process, and open for writing. For example, fid = popen ("ls -ltr / | tail -3", "r"); while (isstr (s = fgets (fid))) fputs (stdout, s); endwhile -| drwxr-xr-x 33 root root 3072 Feb 15 13:28 etc -| drwxr-xr-x 3 root root 1024 Feb 15 13:28 lib -| drwxrwxrwt 15 root root 2048 Feb 17 14:53 tmp - Built-in Function: pclose (FID) Close a file identifier that was opened by `popen'. You may also use `fclose' for the same purpose. - Built-in Function: [IN, OUT, PID] = popen2 (COMMAND, ARGS) Start a subprocess with two-way communication. The name of the process is given by COMMAND, and ARGS is an array of strings containing options for the command. The file identifiers for the input and output streams of the subprocess are returned in IN and OUT. If execution of the command is successful, PID contains the process ID of the subprocess. Otherwise, PID is -1. For example, [in, out, pid] = popen2 ("sort", "-nr"); fputs (in, "these\nare\nsome\nstrings\n"); fclose (in); while (isstr (s = fgets (out))) fputs (stdout, s); endwhile fclose (out); -| are -| some -| strings -| these - Built-in Variable: EXEC_PATH The variable `EXEC_PATH' is a colon separated 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 command line argument `--exec-path PATH', or by setting the value of `EXEC_PATH' in a startup script. If the value of `EXEC_PATH' begins (ends) with a colon, the directories OCTAVE-HOME/libexec/octave/site/exec/ARCH OCTAVE-HOME/libexec/octave/VERSION/exec/ARCH are prepended (appended) to `EXEC_PATH', where OCTAVE-HOME is the top-level directory where all of Octave is installed (the default value is `'). If you don't specify a value for `EXEC_PATH' explicitly, these special directories are prepended to your shell path. In most cases, the following functions simply decode their arguments and make the corresponding Unix system calls. For a complete example of how they can be used, look at the definition of the function `popen2'. - Built-in Function: [PID, MSG] = fork () Create a copy of the current process. Fork can return one of the following values: > 0 You are in the parent process. The value returned from `fork' is the process id of the child process. You should probably arrange to wait for any child processes to exit. 0 You are in the child process. You can call `exec' to start another process. If that fails, you should probably call `exit'. < 0 The call to `fork' failed for some reason. You must take evasive action. A system dependent error message will be waiting in MSG. - Built-in Function: [ERR, MSG] = exec (FILE, ARGS) Replace current process with a new process. Calling `exec' without first calling `fork' will terminate your current Octave process and replace it with the program named by FILE. For example, exec ("ls" "-l") will run `ls' and return you to your shell prompt. If successful, `exec' does not return. If `exec' does return, ERR will be nonzero, and MSG will contain a system-dependent error message. - Built-in Function: [FILE_IDS, ERR, MSG] = pipe () Create a pipe and return the vector FILE_IDS, which corresponding to the reading and writing ends of the pipe. If successful, ERR is 0 and MSG is an empty string. Otherwise, ERR is nonzero and MSG contains a system-dependent error message. - Built-in Function: [FID, MSG] = dup2 (OLD, NEW) Duplicate a file descriptor. If successful, FID is greater than zero and contains the new file ID. Otherwise, FID is negative and MSG contains a system-dependent error message. - Built-in Function: [PID, MSG] = waitpid (PID, OPTIONS) Wait for process PID to terminate. The PID argument can be: -1 Wait for any child process. 0 Wait for any child process whose process group ID is equal to that of the Octave interpreter process. > 0 Wait for termination of the child process with ID PID. The OPTIONS argument can be: 0 Wait until signal is received or a child process exits (this is the default if the OPTIONS argument is missing). 1 Do not hang if status is not immediately available. 2 Report the status of any child processes that are stopped, and whose status has not yet been reported since they stopped. 3 Implies both 1 and 2. If the returned value of PID is greater than 0, it is the process ID of the child process that exited. If an error occurs, PID will be less than zero and MSG will contain a system-dependent error message. - Built-in Function: [ERR, MSG] = fcntl (FID, REQUEST, ARG) Change the properties of the open file FID. The following values may be passed as REQUEST: `F_DUPFD' Return a duplicate file descriptor. `F_GETFD' Return the file descriptor flags for FID. `F_SETFD' Set the file descriptor flags for FID. `F_GETFL' Return the file status flags for FID. The following codes may be returned (some of the flags may be undefined on some systems). `O_RDONLY' Open for reading only. `O_WRONLY' Open for writing only. `O_RDWR' Open for reading and writing. `O_APPEND' Append on each write. `O_NONBLOCK' Nonblocking mode. `O_SYNC' Wait for writes to complete. `O_ASYNC' Asynchronous I/O. `F_SETFL' Set the file status flags for FID to the value specified by ARG. The only flags that can be changed are `O_APPEND' and `O_NONBLOCK'. If successful, ERR is 0 and MSG is an empty string. Otherwise, ERR is nonzero and MSG contains a system-dependent error message. File: octave, Node: Process ID Information, Next: Environment Variables, Prev: Controlling Subprocesses, Up: System Utilities Process, Group, and User IDs ============================ - Built-in Function: getpgrp () Return the process group id of the current process. - Built-in Function: getpid () Return the process id of the current process. - Built-in Function: getppid () Return the process id of the parent process. - Built-in Function: geteuid () Return the effective user id of the current process. - Built-in Function: getuid () Return the real user id of the current process. - Built-in Function: getegid () Return the effective group id of the current process. - Built-in Function: getgid () Return the real group id of the current process. File: octave, Node: Environment Variables, Next: Current Working Directory, Prev: Process ID Information, Up: System Utilities Environment Variables ===================== - Built-in Function: getenv (VAR) Return the value of the environment variable VAR. For example, getenv ("PATH") returns a string containing the value of your path. - Built-in Function: putenv (VAR, VALUE) Set the value of the environment variable VAR to VALUE. File: octave, Node: Current Working Directory, Next: Password Database Functions, Prev: Environment Variables, Up: System Utilities Current Working Directory ========================= - Command: cd DIR - Command: chdir DIR Change the current working directory to DIR. For example, cd ~/octave Changes the current working directory to `~/octave'. If the directory does not exist, an error message is printed and the working directory is not changed. - Built-in Function: pwd () Return the current working directory. - Command: ls OPTIONS - Command: dir OPTIONS List directory contents. For example, ls -l -| total 12 -| -rw-r--r-- 1 jwe users 4488 Aug 19 04:02 foo.m -| -rw-r--r-- 1 jwe users 1315 Aug 17 23:14 bar.m The `dir' and `ls' commands are implemented by calling your system's directory listing command, so the available options may vary from system to system. File: octave, Node: Password Database Functions, Next: Group Database Functions, Prev: Current Working Directory, Up: System Utilities Password Database Functions =========================== Octave's password database functions return information in a structure with the following fields. `name' The user name. `passwd' The encrypted password, if available. `uid' The numeric user id. `gid' The numeric group id. `gecos' The GECOS field. `dir' The home directory. `shell' The initial shell. In the descriptions of the following functions, this data structure is referred to as a PW_STRUCT. - Loadable Function: PW_STRUCT = getpwent () Return a structure containing an entry from the password database, opening it if necessary. Once the end of the data has been reached, `getpwent' returns 0. - Loadable Function: PW_STRUCT = getpwuid (UID). Return a structure containing the first entry from the password database with the user ID UID. If the user ID does not exist in the database, `getpwuid' returns 0. - Loadable Function: PW_STRUCT = getpwnam (NAME) Return a structure containing the first entry from the password database with the user name NAME. If the user name does not exist in the database, `getpwname' returns 0. - Loadable Function: setpwent () Return the internal pointer to the beginning of the password database. - Loadable Function: endpwent () Close the password database. File: octave, Node: Group Database Functions, Next: System Information, Prev: Password Database Functions, Up: System Utilities Group Database Functions ======================== Octave's group database functions return information in a structure with the following fields. `name' The user name. `passwd' The encrypted password, if available. `gid' The numeric group id. `mem' The members of the group. In the descriptions of the following functions, this data structure is referred to as a GRP_STRUCT. - Loadable Function: GRP_STRUCT = getgrent () Return an entry from the group database, opening it if necessary. Once the end of the data has been reached, `getgrent' returns 0. - Loadable Function: GRP_STRUCT = getgrgid (GID). Return the first entry from the group database with the group ID GID. If the group ID does not exist in the database, `getgrgid' returns 0. - Loadable Function: GRP_STRUCT = getgrnam (NAME) Return the first entry from the group database with the group name NAME. If the group name does not exist in the database, `getgrname' returns 0. - Loadable Function: setgrent () Return the internal pointer to the beginning of the group database. - Loadable Function: endgrent () Close the group database. File: octave, Node: System Information, Prev: Group Database Functions, Up: System Utilities System Information ================== - Built-in Function: computer () Print or return a string of the form CPU-VENDOR-OS that identifies the kind of computer Octave is running on. If invoked with an output argument, the value is returned instead of printed. For example, computer () -| i586-pc-linux-gnu x = computer () => x = "i586-pc-linux-gnu" - Built-in Function: isieee () Return 1 if your computer claims to conform to the IEEE standard for floating point calculations. - Built-in Function: version () Return Octave's version number as a string. This is also the value of the built-in variable `OCTAVE_VERSION'. - Built-in Variable: OCTAVE_VERSION The version number of Octave, as a string. - Built-in Function: octave_config_info () Return a structure containing configuration and installation information. - Loadable Function: getrusage () Return a structure containing a number of statistics about the current Octave process. Not all fields are available on all systems. If it is not possible to get CPU time statistics, the CPU time slots are set to zero. Other missing data are replaced by NaN. Here is a list of all the possible fields that can be present in the structure returned by `getrusage': `' `idrss' Unshared data size. `inblock' Number of block input operations. `isrss' Unshared stack size. `ixrss' Shared memory size. `majflt' Number of major page faults. `maxrss' Maximum data size. `minflt' Number of minor page faults. `msgrcv' Number of messages received. `msgsnd' Number of messages sent. `nivcsw' Number of involuntary context switches. `nsignals' Number of signals received. `nswap' Number of swaps. `nvcsw' Number of voluntary context switches. `oublock' Number of block output operations. `stime' A structure containing the system CPU time used. The structure has the elements `sec' (seconds) `usec' (microseconds). `utime' A structure containing the user CPU time used. The structure has the elements `sec' (seconds) `usec' (microseconds). File: octave, Node: Tips, Next: Trouble, Prev: System Utilities, Up: Top Tips and Standards ****************** This chapter describes no additional features of Octave. Instead it gives advice on making effective use of the features described in the previous chapters. * Menu: * Style Tips:: Writing clean and robust programs. * Coding Tips:: Making code run faster. * Documentation Tips:: Writing readable documentation strings. * Comment Tips:: Conventions for writing comments. * Function Headers:: Standard headers for functions. File: octave, Node: Style Tips, Next: Coding Tips, Prev: Tips, Up: Tips Writing Clean Octave Programs ============================= Here are some tips for avoiding common errors in writing Octave code intended for widespread use: * Since all global variables share the same name space, and all functions share another name space, you should choose a short word to distinguish your program from other Octave programs. Then take care to begin the names of all global variables, constants, and functions with the chosen prefix. This helps avoid name conflicts. If you write a function that you think ought to be added to Octave under a certain name, such as `fiddle_matrix', don't call it by that name in your program. Call it `mylib_fiddle_matrix' in your program, and send mail to (bug-octave@bevo.che.wisc.edu) suggesting that it be added to Octave. If and when it is, the name can be changed easily enough. If one prefix is insufficient, your package may use two or three alternative common prefixes, so long as they make sense. Separate the prefix from the rest of the symbol name with an underscore `_'. This will be consistent with Octave itself and with most Octave programs. * When you encounter an error condition, call the function `error' (or `usage'). The `error' and `usage' functions do not return. *Note Errors::. * Please put a copyright notice on the file if you give copies to anyone. Use the same lines that appear at the top of the function files distributed with Octave. If you have not signed papers to assign the copyright to anyone else, then place your name in the copyright notice. File: octave, Node: Coding Tips, Next: Documentation Tips, Prev: Style Tips, Up: Tips Tips for Making Code Run Faster. ================================ Here are some ways of improving the execution speed of Octave programs. * Avoid looping wherever possible. * Use iteration rather than recursion whenever possible. Function calls are slow in Octave. * Avoid resizing matrices unnecessarily. When building a single result matrix from a series of calculations, set the size of the result matrix first, then insert values into it. Write result = zeros (big_n, big_m) for i = over:and_over r1 = ... r2 = ... result (r1, r2) = new_value (); endfor instead of result = []; for i = ever:and_ever result = [ result, new_value() ]; endfor * Avoid calling `eval' or `feval' whenever possible, because they require Octave to parse input or look up the name of a function in the symbol table. If you are using `eval' as an exception handling mechanism and not because you need to execute some arbitrary text, use the `try' statement instead. *Note The try Statement::. * If you are calling lots of functions but none of them will need to change during your run, set the variable `ignore_function_time_stamp' to `"all"' so that Octave doesn't waste a lot of time checking to see if you have updated your function files. File: octave, Node: Documentation Tips, Next: Comment Tips, Prev: Coding Tips, Up: Tips Tips for Documentation Strings ============================== Here are some tips for the writing of documentation strings. * Every command, function, or variable intended for users to know about should have a documentation string. * An internal variable or subroutine of an Octave program might as well have a documentation string. * The first line of the documentation string should consist of one or two complete sentences that stand on their own as a summary. The documentation string can have additional lines that expand on the details of how to use the function or variable. The additional lines should also be made up of complete sentences. * For consistency, phrase the verb in the first sentence of a documentation string as an infinitive with "to" omitted. For instance, use "Return the frob of A and B." in preference to "Returns the frob of A and B«" Usually it looks good to do likewise for the rest of the first paragraph. Subsequent paragraphs usually look better if they have proper subjects. * Write documentation strings in the active voice, not the passive, and in the present tense, not the future. For instance, use "Return a list containing A and B." instead of "A list containing A and B will be returned." * Avoid using the word "cause" (or its equivalents) unnecessarily. Instead of, "Cause Octave to display text in boldface," write just "Display text in boldface." * Do not start or end a documentation string with whitespace. * Format the documentation string so that it fits in an Emacs window on an 80-column screen. It is a good idea for most lines to be no wider than 60 characters. However, rather than simply filling the entire documentation string, you can make it much more readable by choosing line breaks with care. Use blank lines between topics if the documentation string is long. * *Do not* indent subsequent lines of a documentation string so that the text is lined up in the source code with the text of the first line. This looks nice in the source code, but looks bizarre when users view the documentation. Remember that the indentation before the starting double-quote is not part of the string! * The documentation string for a variable that is a yes-or-no flag should start with words such as "Nonzero means...", to make it clear that all nonzero values are equivalent and indicate explicitly what zero and nonzero mean. * When a function's documentation string mentions the value of an argument of the function, use the argument name in capital letters as if it were a name for that value. Thus, the documentation string of the operator `/' refers to its second argument as `DIVISOR', because the actual argument name is `divisor'. Also use all caps for meta-syntactic variables, such as when you show the decomposition of a list or vector into subunits, some of which may vary. File: octave, Node: Comment Tips, Next: Function Headers, Prev: Documentation Tips, Up: Tips Tips on Writing Comments ======================== Here are the conventions to follow when writing comments. `#' Comments that start with a single sharp-sign, `#', should all be aligned to the same column on the right of the source code. Such comments usually explain how the code on the same line does its job. In the Emacs mode for Octave, the `M-;' (`indent-for-comment') command automatically inserts such a `#' in the right place, or aligns such a comment if it is already present. `##' Comments that start with two semicolons, `##', should be aligned to the same level of indentation as the code. Such comments usually describe the purpose of the following lines or the state of the program at that point. The indentation commands of the Octave mode in Emacs, such as `M-;' (`indent-for-comment') and `TAB' (`octave-indent-line') automatically indent comments according to these conventions, depending on the number of semicolons. *Note Manipulating Comments: (emacs)Comments. File: octave, Node: Function Headers, Prev: Comment Tips, Up: Tips Conventional Headers for Octave Functions ========================================= Octave has conventions for using special comments in function files to give information such as who wrote them. This section explains these conventions. The top of the file should contain a copyright notice, followed by a block of comments that can be used as the help text for the function. Here is an example: ## Copyright (C) 1996, 1997 John W. Eaton ## ## This file is part of Octave. ## ## Octave is free software; you can redistribute it and/or ## modify it under the terms of the GNU General Public ## License as published by the Free Software Foundation; ## either version 2, or (at your option) any later version. ## ## Octave is distributed in the hope that it will be useful, ## but WITHOUT ANY WARRANTY; without even the implied ## warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ## PURPOSE. See the GNU General Public License for more ## details. ## ## You should have received a copy of the GNU General Public ## License along with Octave; see the file COPYING. If not, ## write to the Free Software Foundation, 59 Temple Place - ## Suite 330, Boston, MA 02111-1307, USA. ## usage: [IN, OUT, PID] = popen2 (COMMAND, ARGS) ## ## Start a subprocess with two-way communication. COMMAND ## specifies the name of the command to start. ARGS is an ## array of strings containing options for COMMAND. IN and ## OUT are the file ids of the input and streams for the ## subprocess, and PID is the process id of the subprocess, ## or -1 if COMMAND could not be executed. ## ## Example: ## ## [in, out, pid] = popen2 ("sort", "-nr"); ## fputs (in, "these\nare\nsome\nstrings\n"); ## fclose (in); ## while (isstr (s = fgets (out))) ## fputs (stdout, s); ## endwhile ## fclose (out); Octave uses the first block of comments in a function file that do not appear to be a copyright notice as the help text for the file. For Octave to recognize the first comment block as a copyright notice, it must match the regular expression ^ Copyright (C).*\n\n This file is part of Octave. or ^ Copyright (C).*\n\n This program is free softwar (after stripping the leading comment characters). This is a fairly strict requirement, and may be relaxed somewhat in the future. After the copyright notice and help text come several "header comment" lines, each beginning with `## HEADER-NAME:'. For example, ## Author: jwe ## Keywords: subprocesses input-output ## Maintainer: jwe Here is a table of the conventional possibilities for HEADER-NAME: `Author' This line states the name and net address of at least the principal author of the library. ## Author: John W. Eaton <jwe@bevo.che.wisc.edu> `Maintainer' This line should contain a single name/address as in the Author line, or an address only, or the string `jwe'. If there is no maintainer line, the person(s) in the Author field are presumed to be the maintainers. The example above is mildly bogus because the maintainer line is redundant. The idea behind the `Author' and `Maintainer' lines is to make possible a function to "send mail to the maintainer" without having to mine the name out by hand. Be sure to surround the network address with `<...>' if you include the person's full name as well as the network address. `Created' This optional line gives the original creation date of the file. For historical interest only. `Version' If you wish to record version numbers for the individual Octave program, put them in this line. `Adapted-By' In this header line, place the name of the person who adapted the library for installation (to make it fit the style conventions, for example). `Keywords' This line lists keywords. Eventually, it will be used by an apropos command to allow people will find your package when they're looking for things by topic area. To separate the keywords, you can use spaces, commas, or both. Just about every Octave function ought to have the `Author' and `Keywords' header comment lines. Use the others if they are appropriate. You can also put in header lines with other header names--they have no standard meanings, so they can't do any harm. File: octave, Node: Trouble, Next: Installation, Prev: Tips, Up: Top Known Causes of Trouble *********************** This section describes known problems that affect users of Octave. Most of these are not Octave bugs per se--if they were, we would fix them. But the result for a user may be like the result of a bug. Some of these problems are due to bugs in other software, some are missing features that are too much work to add, and some are places where people's opinions differ as to what is best. * Menu: * Actual Bugs:: Bugs we will fix later. * Reporting Bugs:: * Bug Criteria:: * Bug Lists:: * Bug Reporting:: * Sending Patches:: * Service:: File: octave, Node: Actual Bugs, Next: Reporting Bugs, Prev: Trouble, Up: Trouble Actual Bugs We Haven't Fixed Yet ================================ * Output that comes directly from Fortran functions is not sent through the pager and may appear out of sequence with other output that is sent through the pager. One way to avoid this is to force pending output to be flushed before calling a function that will produce output from within Fortran functions. To do this, use the command fflush (stdout) Another possible workaround is to use the command page_screen_output = "false" to turn the pager off. * If you get messages like Input line too long when trying to plot many lines on one graph, you have probably generated a plot command that is too larger for `gnuplot''s fixed-length buffer for commands. Splitting up the plot command doesn't help because replot is implemented in gnuplot by simply appending the new plotting commands to the old command line and then evaluating it again. You can demonstrate this `feature' by running gnuplot and doing something like plot sin (x), sin (x), sin (x), ... lots more ..., sin (x) and then replot sin (x), sin (x), sin (x), ... lots more ..., sin (x) after repeating the replot command a few times, gnuplot will give you an error. Also, it doesn't help to use backslashes to enter a plot command over several lines, because the limit is on the overall command line length, once the backslashed lines are all pasted together. Because of this, Octave tries to use as little of the command-line length as possible by using the shortest possible abbreviations for all the plot commands and options. Unfortunately, the length of the temporary file names is probably what is taking up the most space on the command line. You can buy a little bit of command line space by setting the environment variable `TMPDIR' to be "." before starting Octave, or you can increase the maximum command line length in gnuplot by changing the following limits in the file plot.h in the gnuplot distribution and recompiling gnuplot. #define MAX_LINE_LEN 32768 /* originally 1024 */ #define MAX_TOKENS 8192 /* originally 400 */ Of course, this doesn't really fix the problem, but it does make it much less likely that you will run into trouble unless you are putting a very large number of lines on a given plot. A list of ideas for future enhancements is distributed with Octave. See the file `PROJECTS' in the top level directory in the source distribution. File: octave, Node: Reporting Bugs, Next: Bug Criteria, Prev: Actual Bugs, Up: Trouble Reporting Bugs ============== Your bug reports play an essential role in making Octave reliable. When you encounter a problem, the first thing to do is to see if it is already known. *Note Trouble::. If it isn't known, then you should report the problem. Reporting a bug may help you by bringing a solution to your problem, or it may not. In any case, the principal function of a bug report is to help the entire community by making the next version of Octave work better. Bug reports are your contribution to the maintenance of Octave. In order for a bug report to serve its purpose, you must include the information that makes it possible to fix the bug. If you have Octave working at all, the easiest way to prepare a complete bug report is to use the Octave function `bug_report'. When you execute this function, Octave will prompt you for a subject and then invoke the editor on a file that already contains all the configuration information. When you exit the editor, Octave will mail the bug report for you. * Menu: * Bug Criteria:: * Where: Bug Lists. Where to send your bug report. * Reporting: Bug Reporting. How to report a bug effectively. * Patches: Sending Patches. How to send a patch for Octave. File: octave, Node: Bug Criteria, Next: Bug Lists, Prev: Reporting Bugs, Up: Trouble Have You Found a Bug? ===================== If you are not sure whether you have found a bug, here are some guidelines: * If Octave gets a fatal signal, for any input whatever, that is a bug. Reliable interpreters never crash. * If Octave produces incorrect results, for any input whatever, that is a bug. * Some output may appear to be incorrect when it is in fact due to a program whose behavior is undefined, which happened by chance to give the desired results on another system. For example, the range operator may produce different results because of differences in the way floating point arithmetic is handled on various systems. * If Octave produces an error message for valid input, that is a bug. * If Octave does not produce an error message for invalid input, that is a bug. However, you should note that your idea of "invalid input" might be my idea of "an extension" or "support for traditional practice". * If you are an experienced user of programs like Octave, your suggestions for improvement are welcome in any case. File: octave, Node: Bug Lists, Next: Bug Reporting, Prev: Bug Criteria, Up: Trouble Where to Report Bugs ==================== If you have Octave working at all, the easiest way to prepare a complete bug report is to use the Octave function `bug_report'. When you execute this function, Octave will prompt you for a subject and then invoke the editor on a file that already contains all the configuration information. When you exit the editor, Octave will mail the bug report for you. If for some reason you cannot use Octave's `bug_report' function, send bug reports for Octave to (bug-octave@bevo.che.wisc.edu). *Do not send bug reports to `help-octave'*. Most users of Octave do not want to receive bug reports. Those that do have asked to be on the mailing list. As a last resort, send bug reports on paper to: Octave Bugs c/o John W. Eaton University of Wisconsin-Madison Department of Chemical Engineering 1415 Engineering Drive Madison, Wisconsin 53706 USA File: octave, Node: Bug Reporting, Next: Sending Patches, Prev: Bug Lists, Up: Trouble How to Report Bugs ================== Send bug reports for Octave to one of the addresses listed in *Note Bug Lists::. The fundamental principle of reporting bugs usefully is this: *report all the facts*. If you are not sure whether to state a fact or leave it out, state it! Often people omit facts because they think they know what causes the problem and they conclude that some details don't matter. Thus, you might assume that the name of the variable you use in an example does not matter. Well, probably it doesn't, but one cannot be sure. Perhaps the bug is a stray memory reference which happens to fetch from the location where that name is stored in memory; perhaps, if the name were different, the contents of that location would fool the interpreter into doing the right thing despite the bug. Play it safe and give a specific, complete example. Keep in mind that the purpose of a bug report is to enable someone to fix the bug if it is not known. Always write your bug reports on the assumption that the bug is not known. Sometimes people give a few sketchy facts and ask, "Does this ring a bell?" This cannot help us fix a bug. It is better to send a complete bug report to begin with. Try to make your bug report self-contained. If we have to ask you for more information, it is best if you include all the previous information in your response, as well as the information that was missing. To enable someone to investigate the bug, you should include all these things: * The version of Octave. You can get this by noting the version number that is printed when Octave starts, or running it with the `-v' option. * A complete input file that will reproduce the bug. A single statement may not be enough of an example--the bug might depend on other details that are missing from the single statement where the error finally occurs. * The command arguments you gave Octave to execute that example and observe the bug. To guarantee you won't omit something important, list all the options. If we were to try to guess the arguments, we would probably guess wrong and then we would not encounter the bug. * The type of machine you are using, and the operating system name and version number. * The command-line arguments you gave to the `configure' command when you installed the interpreter. * A complete list of any modifications you have made to the interpreter source. Be precise about these changes--show a context diff for them. * Details of any other deviations from the standard procedure for installing Octave. * A description of what behavior you observe that you believe is incorrect. For example, "The interpreter gets a fatal signal," or, "The output produced at line 208 is incorrect." Of course, if the bug is that the interpreter gets a fatal signal, then one can't miss it. But if the bug is incorrect output, we might not notice unless it is glaringly wrong. Even if the problem you experience is a fatal signal, you should still say so explicitly. Suppose something strange is going on, such as, your copy of the interpreter is out of synch, or you have encountered a bug in the C library on your system. Your copy might crash and the copy here would not. If you said to expect a crash, then when the interpreter here fails to crash, we would know that the bug was not happening. If you don't say to expect a crash, then we would not know whether the bug was happening. We would not be able to draw any conclusion from our observations. Often the observed symptom is incorrect output when your program is run. Unfortunately, this is not enough information unless the program is short and simple. It is very helpful if you can include an explanation of the expected output, and why the actual output is incorrect. * If you wish to suggest changes to the Octave source, send them as context diffs. If you even discuss something in the Octave source, refer to it by context, not by line number, because the line numbers in the development sources probably won't match those in your sources. Here are some things that are not necessary: * A description of the envelope of the bug. Often people who encounter a bug spend a lot of time investigating which changes to the input file will make the bug go away and which changes will not affect it. Such information is usually not necessary to enable us to fix bugs in Octave, but if you can find a simpler example to report *instead* of the original one, that is a convenience. Errors in the output will be easier to spot, running under the debugger will take less time, etc. Most Octave bugs involve just one function, so the most straightforward way to simplify an example is to delete all the function definitions except the one in which the bug occurs. However, simplification is not vital; if you don't want to do this, report the bug anyway and send the entire test case you used. * A patch for the bug. Patches can be helpful, but if you find a bug, you should report it, even if you cannot send a fix for the problem. File: octave, Node: Sending Patches, Next: Service, Prev: Bug Reporting, Up: Trouble Sending Patches for Octave ========================== If you would like to write bug fixes or improvements for Octave, that is very helpful. When you send your changes, please follow these guidelines to avoid causing extra work for us in studying the patches. If you don't follow these guidelines, your information might still be useful, but using it will take extra work. Maintaining Octave is a lot of work in the best of circumstances, and we can't keep up unless you do your best to help. * Send an explanation with your changes of what problem they fix or what improvement they bring about. For a bug fix, just include a copy of the bug report, and explain why the change fixes the bug. * Always include a proper bug report for the problem you think you have fixed. We need to convince ourselves that the change is right before installing it. Even if it is right, we might have trouble judging it if we don't have a way to reproduce the problem. * Include all the comments that are appropriate to help people reading the source in the future understand why this change was needed. * Don't mix together changes made for different reasons. Send them *individually*. If you make two changes for separate reasons, then we might not want to install them both. We might want to install just one. * Use `diff -c' to make your diffs. Diffs without context are hard for us to install reliably. More than that, they make it hard for us to study the diffs to decide whether we want to install them. Unidiff format is better than contextless diffs, but not as easy to read as `-c' format. If you have GNU diff, use `diff -cp', which shows the name of the function that each change occurs in. * Write the change log entries for your changes. Read the `ChangeLog' file to see what sorts of information to put in, and to learn the style that we use. The purpose of the change log is to show people where to find what was changed. So you need to be specific about what functions you changed; in large functions, it's often helpful to indicate where within the function the change was made. On the other hand, once you have shown people where to find the change, you need not explain its purpose. Thus, if you add a new function, all you need to say about it is that it is new. If you feel that the purpose needs explaining, it probably does--but the explanation will be much more useful if you put it in comments in the code. If you would like your name to appear in the header line for who made the change, send us the header line. File: octave, Node: Service, Prev: Sending Patches, Up: Trouble How To Get Help with Octave =========================== The mailing list (help-octave@bevo.che.wisc.edu) exists for the discussion of matters related to using and installing Octave. If would like to join the discussion, please send a short note to (help-octave*-request*@bevo.che.wisc.edu). *Please do not* send requests to be added or removed from the mailing list, or other administrative trivia to the list itself. If you think you have found a bug in the installation procedure, however, you should send a complete bug report for the problem to (bug-octave@bevo.che.wisc.edu). *Note Bug Reporting:: for information that will help you to submit a useful report.