Can I specify a portion of the image to render in Cycles?
Render just part of a final image from Cycles?
Recently, I was in a car and noticed a plane in the sky. What was interesting was that the plane seemed to go slower than my car because I passed the plane. Is there a physics reason to this? Why is my attempt at downloading Big Sur failing? I am currently using a MacBook Pro 13&quot; Mid 2018 with Touch Bar. Today macOS Big Sur was released and I tried to download it but it's getting stuck at 484.4 MB. Initially, it shows 16-17 minutes left, but as soon as it reaches 484.4 MB it's stuck and the timer goes till 10 hours! My Wi-Fi is totally stable with a speed of 100 Mbps. I tried to restart my Mac but it still gets stuck. Earlier there were similar issues in the App Store (even now they are). The issue was I was not able to download an app unless I connect to the US VPN. I even contacted support but they were not able to help out. It wasn't a big deal as a VPN could be used. But now even with VPN, it gets stuck. A matrix $M$ that commutes with any matrix is of the form $M=\alpha I$ What is a simple way to create a binary relation symbol on top of another? What is a simple way to have \ll on top of \gg with equal size and vertically center aligned and have them work as a binary relation symbol like \lessgtr? The commands \underset and \overset cannot be used because they do not treat the two symbols equally, and they do not vertically center. Extract single file from tar to other folder I've searched for multiple forums for this questions and have seen different answers but so far, nothing have worked yet even from the ones I've seen here.  I want to extract a single file from a tar to a different directory.  I've tried this:  tar xvf file.tar -C /home/dir/ filename   or this:  tar -x filename -f file.tar -C /home/dir   But got these errors respectively:  x filename, 14826 bytes, 29 media blocks. File -C not present in the archive. File /home/dir not present in the archive.   and:  tar: /dev/rmt0: A file or directory in the path name does not exist.   The first extracted the file but in the same directory, not to the folder I wanted. Using first person or third person in papers? What is the significance of a mostly blank user card? I've been using Texmaker for ~5 years now and prefer it over other editors because of its flexibility.   Is there a way to auto-indent LaTeX code in TeXmaker so that the code becomes more manageable ? Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache?    Note that this is mostly useful for benchmarking. Emptying the buffers and cache reduces performance! If you're here because you thought that freeing buffers and cache was a positive thing, go and read . The short story: free memory is unused memory is wasted memory. When you use the allowframebreaks option in beamer then you get additional frames if the content is too high for one frame. The vertical spacing gets disturbed when you use a list (itemize, enumerate, description), for example, see the following animation. I used the t option (for top alignment) for the frame.     \documentclass[aspectratio=169]{beamer}   \begin{document}  \begin{frame}[t,allowframebreaks] \frametitle{Frame Title} \setlength{\mylength}{\baselineskip} \begin{itemize} \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \end{itemize}  \end{frame}  \begin{frame}[t,allowframebreaks] \frametitle{Frame Title}  Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\ Text\\  \end{frame}  \end{document}    I thought of a solution, when I read  question where they explain the different length in lists. The main idea is to check if the current frame is not the first frame of a frame continuation and add the needed vertical space. I thought that \topsep is the needed length but apparently, it is not quite right. It ist almost perfect but it still "dances" a little bit. Which additional length do I need? Here's the animation and the used code.     \documentclass[aspectratio=169]{beamer}  \setbeamertemplate{frametitle continuation}{%     (\insertcontinuationcount)%     \ifnum\insertcontinuationcount&gt;1%     \vspace*{\topsep}%     \else%     %     \fi% }  \begin{document}  \begin{frame}[t,allowframebreaks] \frametitle{Frame Title}  \begin{itemize} \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \item Test \end{itemize}  \end{frame}  \end{document}   Related        Definition of \itemize in beamer  In beamerbaselocalstructure.sty I found  \renewcommand{\itemize}[1][]{%   \beamer@ifempty{#1}{}{\def\beamer@defaultospec{#1}}%   \ifnum \@itemdepth &gt;2\relax\@toodeep\else     \advance\@itemdepth\@ne     \beamer@computepref\@itemdepth% sets \beameritemnestingprefix     \usebeamerfont{itemize/enumerate \beameritemnestingprefix body}%     \usebeamercolor[fg]{itemize/enumerate \beameritemnestingprefix body}%     \usebeamertemplate{itemize/enumerate \beameritemnestingprefix body begin}%     \list       {\usebeamertemplate{itemize \beameritemnestingprefix item}}       {\def\makelabel##1{%           {%             \hss\llap{{%                 \usebeamerfont*{itemize \beameritemnestingprefix item}%                 \usebeamercolor[fg]{itemize \beameritemnestingprefix item}##1}}%           }%         }%       }   \fi%   \beamer@cramped%   \raggedright%   \beamer@firstlineitemizeunskip% }   But I do not understand where the different kinds of spaces are defined that cause the "dancing".  "Evil" Stuff in beamer  Motivated by the comment of @cfr I searched the beamer documentation for "evil" stuff -- this is what I have found (beamer guide version 3.41):   Do not use subsubsections, they are evil. Never ever use the evil option shrink.  Using this [again shrink] option is very evil. The use of this [allowframebreaks] option is evil. How to properly hook up various maps types in Cycles? I created some texture maps in MindTex to use in Blender, but I can't figure out how to properly hook them up. The maps I have:  - Diffuse  - Normal  - Height   - Specular   - Gloss   - Self Illumination  - Reflection  - Ambient Occlusion   MindTex (left) vs. Blender (right)  As you can clearly see it's a pretty big difference.  is my material node setup in Blender. In the examples I don't actually use self illumination or reflection images, but including this in the answer would be helpful. How to control fan speed? How can I control the computer's fan speed?  On Windows there is a wonderful program called . Overriding the java equals() method - not working? Windows 7 + Deep Freeze - I'm stuck in an endless reboot loop I have the following setup:   Windows 7 Ultimate Deep Freeze   I "thawed" my machine last night and performed a Windows Update. The update is having issues (it gets stuck at 32%, fails, and restarts my machine). When it reboots it attempts it again, and again, and again, etc. (Endless loop).  I looked online and found some solutions, but none of them seem to be working:   When I run Safe Mode, Safe Mode w/ Network, or Safe Mode w/ Command Prompt it attempts to revert the Windows Update changes. However, the problem is with Deep Freeze on (and now in "Frozen" mode) the reverted changes don't stay, and I'm back into the loop of death. Oh, and side note: "Safe Mode w/ Command Prompt" does not actually take me to a command prompt window? Perhaps because it is attempting to complete the Windows Update changes first? I have tried to select the option to NOT restart when an windows error occurs, but it still does. I tried the remainder of all the other options in the F8 screen.     The only other option left is to find my Windows 7 Media Disc (I can't find it right now) and use it to repair windows (because for some reason the repair option does not show up in the F8 screen).  Is there a way to disable Deep Freeze from loading? When I selected "Safe Mode w/ Command Prompt" I noticed that it loads the DpFrz.sys file. I know that when I'm in the Windows Boot Manager if I press F10 instead of F8 (while highlighting Windows 7) it takes me to an "Edit Boot Options" screen:     Edit Windows boot options for: Windows 7      Path: \Windows\system32\winload.exe      Partition: 2 Hard Disk: 8e90e329      [ /NOEXECUTE=OPTIN (I CAN EDIT THIS LINE)   ]     Update: I found my Windows 7 Media Disk and it did not help out. The laptop had the "System Restore" as a partition on the HDD. I later received (in the mail) a Windows 7 Upgrade Disc from Sony to upgrade my system from Windows Vista to Windows 7 Ultimate. I placed the disc into the DVD drive and it does not come up as a "bootable" disc. I'm going to try to find an alternative disc to see if I can get into Command Prompt.    Update 2: I got a Windows Repair disc and got into a command prompt window. I got into the registry and disabled Deep Freeze. Also:   I renamed the Pending.xml file to Pending.old I cleared out the Windows Temp directory   I still am stuck in the loop (though, it isn't an issue with DeepFreeze anymore because I can make changes to the hard drive and they persist). Not sure what to do at this point?    Update 3: I ran the repair option and it couldn't repair, but it did point me to something. It says the error was due to a driver that was failing. I have a feeling it is my UPEK Fingerprint scanner. Explain travel times and distances on flight A flight from Los Angeles to ABQ is about 2 hours but is ~670.2 miles  A flight from San Jose to Chicago is 4 hours but is ~1859.0 miles  Can anyone explain why the travel time from San Jose to Chicago is not longer and closer to 5.75 hours?  If the distance increase by 2, shouldn't the time increase by a factor of 2 as well? Settings API enable default settings on theme install? I am still learning settings API so please forgive my noob question. I have three fields: a checkbox, colorpicker and text field (they are working), but I would like to do this: when the theme is installed add "checked" state to my checkbox but allow user to "unchecked" it ,and if empty add default color to my colorpicker... I have no idea how to do this so please help me!  My code looks like this now (thanks to @Chip Bennett! ) :  &lt;?php add_action('admin_menu','create_theme_options_page'); function create_theme_options_page(){ add_options_page('Theme Options','Theme Options','administrator',__FILE__,'build_options_page'); }    function build_options_page(){    ?&gt;    &lt;div id="theme-options-wrap"&gt;    &lt;div style="float:left;margin-top:19px;position:absolute;" class="icon32" id="icon-tools"&gt;&lt;br/&gt;&lt;/div&gt;    &lt;h2&gt;My options page&lt;/h2&gt;    &lt;form method="post" action="options.php"&gt;    &lt;?php settings_fields('plugin_options');?&gt;    &lt;?php do_settings_sections(__FILE__); ?&gt;    &lt;p class="submit"&gt;    &lt;input name="Submit" type="submit" class="button-primary" value="&lt;?php esc_attr_e('Save changes');?&gt;"/&gt;    &lt;/p&gt;    &lt;/form&gt;    &lt;/div&gt;    &lt;?php    }       add_action('admin_init','register_and_build_fields');      function register_and_build_fields(){      register_setting('plugin_options','plugin_options','validate_setting');      add_settings_section('main_section','&lt;br/&gt;&lt;br/&gt;Main Settings','section_cb',__FILE__);      add_settings_field('banner_heading','Banner Heading:','banner_heading_setting',__FILE__,'main_section');      add_settings_field('display_sidebar','Display Sidebar:','display_sidebar_setting',__FILE__,'main_section');      add_settings_field('display_colorpicker','Display Colorpicker:','display_colorpicker_setting',__FILE__,'main_section');      }        //Install Iris colorpicker        add_action( 'admin_enqueue_scripts', 'mw_enqueue_color_picker' );        function mw_enqueue_color_picker( $hook_suffix ) {        // first check that $hook_suffix is appropriate for your admin page        wp_enqueue_style( 'wp-color-picker' );        wp_enqueue_script( 'my-script-handle', get_template_directory_uri() . '/js/my-script.js', array( 'wp-color-picker' ), false, true );        }           //Colorpicker          //Now how to add a default color on theme install?          function display_colorpicker_setting(){          $options = get_option('plugin_options');          echo"&lt;input type='text' id='color1' name='plugin_options[display_colorpicker]' value='{$options['display_colorpicker']}'/&gt;";          }            //Sidebar checkbox           //Now how to add a default state "checked" on theme install?           function display_sidebar_setting(){           $options = get_option('plugin_options');           echo "&lt;input type='checkbox' name='plugin_options[display_sidebar]' {$options['display_sidebar']} id='display_sidebar' /&gt;";           }              //Banner Heading             function banner_heading_setting(){             $options = get_option('plugin_options');             echo "&lt;input name='plugin_options[banner_heading]' type='text' value='{$options['banner_heading']}'/&gt;";             }               //Validate our settings here               function validate_setting($plugin_options){                  return $plugin_options;               }                 function section_cb(){                } ?&gt; which novel involved sending instantaneous tachyon body copies around the galaxy, mostly to die? The novel centers around a man living a comfortable existence in the pretty distant future.  To support himself, he is occasionally asked to enter a box which will copy his entire body, and send it out faster than the speed of light to some developing world, to work.  His copy on this world wakes up and realizes what a big mistake he's made.  The copy does grueling work, feels lonely, and eventually just dies of radiation sickness.  Back on earth, the man never realizes how bad it is out there, and keeps sending out more copies.  I think the story is probably 80s or earlier - not sure if it's a short story, or the beginning of a novel which I lost &amp; never finished. LINQ on a LinkedList - iterate over LinkedListNode, not T Asymptotic distribution of maximum order statistic of IID random normals Is there a nice limiting distribution of $\max( X_1,X_2,...,X_n) $ as $n$ goes to $\infty$, assuming that they are iid normal distributions with variance $\sigma^2$.   This is almost certainly a well known problem with a clever proof and nice solution, but I've been digging around and haven't found anything. Regular Expression to match valid dates