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* Search for an answer in our [https://lists.gnu.org/archive/html/help-octave/ mailing list archives]
* Search for an answer in our [https://lists.gnu.org/archive/html/help-octave/ mailing list archives]
* Contact our user community using our [https://octave.discourse.group Octave Discourse].
* Contact our user community using our [https://lists.gnu.org/mailman/listinfo/help-octave help@octave.org mailing list] (feel free to subscribe to this mailing list for the latest updates and discussions)
* Contact our user community using our [https://webchat.freenode.net/?channels=octave IRC chat room <code>#octave</code> in Freenode]
* Contact our user community using our [https://webchat.freenode.net/?channels=octave IRC chat room <code>#octave</code> in Freenode]


<div class="tocinline">__TOC__</div>
<div class="tocinline">__TOC__</div>
=== Support expectations ===
See [https://octave.org/support-expectations.html Support Expectations]
Also this [https://www.commitstrip.com/en/2014/05/07/the-truth-behind-open-source-apps/ CommitStrip]


=General=
=General=
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   John W. Eaton, David Bateman, Søren Hauberg, Rik Wehbring ({{Release Year}}).
   John W. Eaton, David Bateman, Søren Hauberg, Rik Wehbring ({{Release Year}}).
   GNU Octave version {{Release}} manual: a high-level interactive language for numerical computations.
   GNU Octave version {{Release}} manual: a high-level interactive language for numerical computations.
   URL https://octave.org/doc/v{{Release}}/
   URL https://www.gnu.org/software/octave/doc/v{{Release}}/


A [https://en.wikipedia.org/wiki/BibTeX BibTeX] entry for [https://en.wikipedia.org/wiki/LaTeX LaTeX] users is:
A [https://en.wikipedia.org/wiki/BibTeX BibTeX] entry for [https://en.wikipedia.org/wiki/LaTeX LaTeX] users is:
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     author    = {John W. Eaton and David Bateman and S{\o}ren Hauberg and Rik Wehbring},
     author    = {John W. Eaton and David Bateman and S{\o}ren Hauberg and Rik Wehbring},
     year      = <span>{</span>{{Release Year}}},
     year      = <span>{</span>{{Release Year}}},
     url      = {[https://octave.org/doc/v{{Release}}/ https://octave.org/doc/v{{Release}}/]},
     url      = {https://www.gnu.org/software/octave/doc/v{{Release}}/},
   }
   }


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The following steps have been the solution to several bug reports and help requests.  Please try them before asking for further support.  If nothing below helps, please give us the following information:
The following steps have been the solution to several bug reports and help requests.  Please try them before asking for further support.  If nothing below helps, please give us the following information:


* Operating system: e.g. [https://support.microsoft.com/en-us/help/13443/windows-which-version-am-i-running '''MS Windows 10 (version 2004)'''] or '''Ubuntu 20.04'''
* Operating system: e.g. [https://support.microsoft.com/en-us/help/13443/windows-which-version-am-i-running '''Windows 10 (version 1909)'''] or '''Ubuntu 20.04'''
* GNU Octave version: e.g. '''Version {{Release}}'''
* GNU Octave version: e.g. '''Version {{Release}}'''
* Installation method: e.g. '''Downloaded and installed "octave-{{Release}}-w64-installer.exe" from https://www.octave.org/download.html'''
* Installation method: e.g. '''Downloaded and installed "octave-{{Release}}-w64-installer.exe" from https://www.octave.org/download.html'''
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=== MS Windows ===
=== MS Windows ===


* After Octave upgrade the GUI does not open / shuts down immediately.
* After upgrade the GUI does not open / shuts down immediately.
** '''Solution:'''
** '''Solution:''' Delete the folder {{path|C:\Users\YOUR_USER_NAME\.config\octave}}
*** Version 5.2.0 and older: Delete the folder {{path|C:\Users\YOUR_USER_NAME\.config\octave}}
*** Version 6.1.0 and newer: Delete the folder {{path|%APPDATA%\octave}}, which generally is located at {{path|C:\Users\YOUR_USER_NAME\AppData\Roaming\octave}}
* Missing/conflicting files.
* Missing/conflicting files.
** '''Solution:''' Remove/Uninstall all existing Octave versions.  Restart the system.  Install GNU Octave again.
** '''Solution:''' Remove/Uninstall all existing Octave versions.  Restart the system.  Install GNU Octave again.
 
* Permission errors.
* Permission errors
** '''Solution 1:''' Consult your malware detection (a.k.a. AntiVirus) software, if files are blocked.
** '''Solution 1:''' Octave versions prior to version 7.1.0 on MS Windows used VBS scripts to start the program.  You can test whether your system is blocking VBS scripts by doing the following:
** '''Solution 2:''' Did you install Octave on a network-drive?  Do you have the execution permissions?
**# Using Notepad or another text editor, create a text file containing only the text: <pre>msgbox("This is a test script, Click OK to close")</pre>
**# Save the file on your Desktop with the name {{Path|testscript.vbs}} (be sure that the editor didn't end it in .txt or .vbs.txt).
**# Double click the file.  If scripts can run, a popup window will appear with that message.
**#* If the file opens in notepad or an editor, it means it still ended in .txt.  MS Windows insecurely hides file extensions by default.  To show file extensions follow [https://answers.microsoft.com/en-us/windows/forum/all/in-win10-how-to-show-the-file-extension-for/ed21ff20-cdb3-4263-9c7d-fc6ed125fc82 these instructions at Microsoft.com].
**#* If both {{Path|testscript.vbs}} and {{Path|octave.vbs}} open a text- or other editor, it means your MS Windows file associations have .vbs files associated with another program.  To fix this, right click the .vbs file, select "Open With", select "Choose Another App", check the box that says "Always use this app to open .vbs files".  Finally, select "Microsoft Windows Based Script Host" from the list.  If it is not in the list, select "More apps".  If still not there, select "Look for Another App on this PC" and navigate to {{Path|C:\Windows\System32\wscript.exe}}, select it, and select "Open".  If {{Path|wscript}} is still not present you will need to seek assistance installing missing MS Windows components.
**# Try moving {{Path|testscript.vbs}} to another location, such as a {{Path|C:\temp folder}}.  Additionally try to move {{Path|testscript.vbs}} in the Octave installation folder containing {{Path|octave.vbs}} and see if VBS scripts can be run there.
**# If {{Path|testscript.vbs}} doesn't run in any of those locations, then scripting appears to be disabled or blocked on your system.  If {{Path|testscript.vbs}} runs in some locations but not others, there there may be other security permissions errors to be solved.  If {{Path|testscript.vbs}} runs in the same folder as {{Path|octave.vbs}}, but directly double-clicking on {{Path|octave.vbs}} does not start Octave, then there appears to be some problem other than script permissions.
** '''Solution 2:''' Consult your malware detection (a.k.a. AntiVirus) software, if files are blocked.
** '''Solution 3:''' Did you install Octave on a network-drive?  Do you have the execution permissions?
** '''Solution 4:''' Is your computer managed by your company?  Does your administrator prohibit script execution?
===Collecting gdb backtrace information===
The following instructions can help you gather troubleshooting information that may help developers identify the problem if the above steps are ineffective:
* if Octave is 'hanging' (the process is remaining open):
*# attempt to start the Octave GUI
*# with the program stalled (either at the GUI, or with the black terminal window), open the Task Manager (right click on taskbar, select Task manager), switch to the "Details" tab, find `octave-gui.exe` on that list, ad take note of the corresponding PID (process ID)
*# Open the folder where Octave is installed. You should find a file called `cmdshell.bat` in the main folder. Run that file, which should open a MSYS2 bash (command line) window.
*# At that prompt, run `gdb -p <em>PID</em>` where <em>PID</em> is the process ID noted previously.
*# at the gdb prompt, execute `set logging on` to save all output to a text file (default will be `gdb.txt`. If you want a different location or filename you can execute `set logging file C:\path\to\file.txt` first).
*# execute `thread apply all bt`.  (If this returns a list longer than one page you may need to 'continue' by typing `c`.)
*# execute `quit` to leave gdb.
*# append that text file to your trouble report at octave.discourse.group or bug report at bugs.octave.org.
 
* if Octave is immediately crashing and closing:
*# Open the folder where Octave is installed. You should find a file called `cmdshell.bat` in the main folder. Run that file, which should open a MSYS2 bash (command line) window.
*# At that prompt, run `gdb octave`. (that will start gdb attached to the octave executable.)
*# at the gdb prompt, execute `set logging on` to save all output to a text file (default will be `gdb.txt`. If you want a different location or filename you can execute `set logging file C:\path\to\file.txt` first).
*# At the gdb prompt, execute `r --gui`.  That should attempt to start the Octave in GUI mode.  The gdb prompt should stay unresponsive as long as octave is running.
*# If octave crashes, the gdb prompt should become responsive again. execute `thread apply all bt`.  (If this returns a list longer than one page you may need to 'continue' by typing `c`.)
*# append the text file to your trouble report at octave.discourse.group or bug report at bugs.octave.org.


==I do not see any output of my script until it has finished?==
==I do not see any output of my script until it has finished?==
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==Why is Octave's floating-point computation wrong?==
==Why is Octave's floating-point computation wrong?==


Floating-point arithmetic is an approximation '''in binary''' to arithmetic on real or complex numbers.  Just like you cannot represent 1/3 exactly in decimal arithmetic (0.333333... is only a rough approximation to 1/3 for any finite number of 3s), you cannot represent some fractions like <math>1/10</math> exactly in base 2.  In binary, the representation to one tenth is <math>0.0\overline{0011}_b</math> where the bar indicates that it repeats infinitely (like how <math>1/6 = 0.1\overline{6}_d</math> in decimal).  Because this infinite repetition cannot be represented exactly with a finite number of digits, rounding errors occur for values that appear to be exact in decimal but are in fact approximations in binary, such as for example how 0.3 - 0.2 - 0.1 is not equal to zero.
Floating-point arithmetic is an approximation '''in binary''' to arithmetic on real or complex numbers.  Just like you cannot represent 1/3 exactly in decimal arithmetic (0.333333... is only a rough approximation to 1/3), you cannot represent some fractions like <math>1/10</math> exactly in base 2.  In binary, the representation to one tenth is <math>0.0\overline{0011}_b</math> where the bar indicates that it repeats infinitely (like how <math>1/6 = 0.1\overline{6}_d</math> in decimal).  Because this infinite repetition cannot be represented exactly with a finite number of digits, rounding errors occur for values that appear to be exact in decimal but are in fact approximations in binary, such as for example how 0.3 - 0.2 - 0.1 is not equal to zero.


In addition, some advanced operations are computed by approximation and there is no guarantee for them to be accurate, see [https://en.wikipedia.org/wiki/Rounding#Table-maker.27s_dilemma Table-maker's dilemma] for further references. Their results are system-dependent.
In addition, some advanced operations are computed by approximation and there is no guarantee for them to be accurate, see [https://en.wikipedia.org/wiki/Rounding#Table-maker.27s_dilemma Table-maker's dilemma] for further references. Their results are system-dependent.
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This is one of those times where the best documentation is to read the existing code.  We have three different toolkits in Octave now, so there are some examples to draw from.
This is one of those times where the best documentation is to read the existing code.  We have three different toolkits in Octave now, so there are some examples to draw from.


= Development =
=Development=
 
==When will feature X be released or implemented?==
 
When it's ready, sooner [http://www.octave.org/get-involved.html if you help].  You can [https://savannah.gnu.org/patch/?group=octave send us patches] if you can implement feature X yourself.  If you can't, some [http://www.octave.org/commercial-support.html developers may be convinced to work on your specific problem for some money].
 
==How can I get involved in Octave development?==


== When will feature X be released or implemented? ==
Be around.  Be social.  Participate in our mailing lists [https://lists.gnu.org/mailman/listinfo/help-octave help@octave.org] and [https://lists.gnu.org/mailman/listinfo/octave-maintainers maintainers@octave.org].  Find things about Octave you don't like, and start thinking about how to fix them.  Many people who now contribute to Octave first spent several years helping in the mailing list before they started to delve into the code.  A good way to learn Octave is to understand the problems other people are having with it, so being helpful in the mailing lists not only helps Octave as a whole, but it also prepares you to be a better Octave contributor.


When it's ready, sooner [https://www.octave.org/get-involved.html if you help].  You can [https://savannah.gnu.org/patch/?group=octave send us patches] if you can implement feature X yourselfIf you can't, some [https://www.octave.org/commercial-support.html developers may be convinced to work on your specific problem for some money].
If you feel ready to dive right into the code, read the [[Developers]] wiki page or [http://www.octave.org/get-involved.html start here].  But do not send an email to the mailing lists listing your skills and offering to helpWe won't just suggest things for you to do.  We lack volunteers and we do need your help, but because of that, we also lack the time to provide good guidance and mentoring. If there is a specific short-term project you would like to work on, say so, and just do it.  Then ask for help or advice when you're doing it.  It is a lot more important that you do something that you're actually interested on than something we suggested because it only matches your skills.


== How can I get involved in Octave development? ==
We also need help with this wiki and the [http://www.octave.org/doc/interpreter/ manual].  These are also important tasks.  The documentation is easy to patch, and the help text for individual functions even more so.  Editing this wiki is even easier.


:''See [[Developer FAQ]]''.
Accurate bug reporting is also very useful.  Find and report [http://bugs.octave.org/ bugs], making an attempt to diagnose them.  Eventually, you will also know how to fix them.  If you want to help with bug reports or patches, subscribe to the [https://lists.gnu.org/mailman/listinfo/octave-bug-tracker bug tracker mailing list].  You'll get updates on all bug activity, and you can jump in when you see
something you can help with.


[[Category:FAQ]]
Look at our [[projects]], [[short projects]], and [[Summer of Code - Getting Started]] if you need specific inspiration for coding tasks that we would like to get done.
Please note that all contributions to Octave may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Octave:Copyrights for details). Do not submit copyrighted work without permission!

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