This is my first time with Ubuntu (or any Linux distro for that matter).  I installed Ubuntu 14.04 alongside windows 7. The initial install went flawlessly without any errors. After the install, I was able to login with the user I created, and then it booted up to a blank purplish screen. The only thing showing is my cursor. Left or right clicking doesn't bring up any options. I left it for an hour thinking it is still installing. Still has the blank screen. I reloaded the DVD thinking I will get a 'repair' option, but only get 'Try Ubuntu' and 'install Ubuntu'. This is on a dell laptop. Can anyone please give me a detailed step by step fix? My first experience with Ubuntu isn't going too well.
When I login, nothing happens.   I am presented with my desktop wallpaper.    No Dash, no Launcher, nothing.
Play a short sound in iOS Create database fields to an existing table when installing a module I'm new to drupal and I need some help.  I created a new module with name user_extra. Which create necessery table when Installing the module.  But I also need to insert some database field in 'users_field_data' table ('user_extra_id' and 'user_office')  In baseFieldDefinitions I wrote all necessery database table fields for user_extra table.   public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {     // Standard field, used as a unique if primary index.     $fields['id'] = BaseFieldDefinition::create('integer')         -&gt;setLabel(t('Unit ID'))         -&gt;setDescription(t('The unit ID.'))         -&gt;setReadOnly(TRUE)         -&gt;setSetting('unsigned', TRUE);      $fields['uuid'] = BaseFieldDefinition::create('uuid')         -&gt;setLabel(t('UUID'))         -&gt;setDescription(t('The unit UUID.'))         -&gt;setReadOnly(TRUE);         .         .         .     $fields['user_info'] = BaseFieldDefinition::create('string')         -&gt;setLabel(t('User Info'))         -&gt;setDescription(t("The User Info"))         -&gt;setSetting('max_length', 255)         -&gt;setDisplayOptions('form', array(           'type' =&gt; 'string_textfield',           'weight' =&gt; 10,         ))         -&gt;setDisplayConfigurable('form', TRUE);      return $fields;      }   When I install the module it inserts all values that I define in baseFieldDefinitions.  But I also need to create 'user_extra_id' and 'user_office' in 'users_field_data' table with setDisplayOptions and setDisplayConfigurable options.  This is the commenting that I made in entity file  /**  * @ContentEntityType(  *   id = "user_extra",  *   label = @Translation("user extra"),  *   handlers = {  *     "storage" = "Drupal\user_extra\UserextraStorage",  *     "storage_schema" = "Drupal\user_extra\UserextraStorageSchema",  *     "access" = "Drupal\user_extra\UserextraAccessControlHandler",  *     "list_builder" = "Drupal\user_extra\UserextraListBuilder",  *     "view_builder" = "Drupal\user_extra\UserextraViewBuilder",  *     "views_data" = "Drupal\user_extra\UserextraViewsData",  *     "form" = {  *       "default" = "Drupal\user_extra\Form\UserextraForm",  *       "add" = "Drupal\user_extra\Form\UserextraAddForm",  *       "edit" = "Drupal\user_extra\Form\UserextraEditForm",  *       "delete" = "Drupal\user_extra\Form\UserextraDeleteForm",  *     }  *   },  *   admin_permission = "administer user_extra",  *   base_table = "user_extra",  *   entity_keys = {  *     "id" = "id",  *     "label" = "name",  *     "uuid" = "uuid",  *   },  *   links = {  *     "canonical" = "/admin/user_extra/{user_extra}",  *     "add-form" = "/admin/user_extra/add",  *     "delete-form" = "/admin/user_extra/{user_extra}/delete",  *     "overview-form" = "/admin/user_extra/${user_extra}/overview",  *     "edit-form" = "/admin/user_extra/{user_extra}",  *     "collection" = "/admin/user_extra",  *     "children" = "/admin/user_extra/{user_extra}/children",  *   },  * )  */ Find the solution of following differential equation:     $$\frac{dy}{dx}=\frac{1}{xy(x^2 \sin (y^2)+1)}$$   Could someone hint me something to get through this problem? I want to show for $x\in\mathbb{R}$, the following inequality holds. $$ \left|\sin x\right|+\left|\sin (x+1)\right|+\left|\sin (x+2)\right|&gt;8/5. $$ This trigonometric inequality has been verified by Mathematica using the Plot commend. However, using the sum formula for the sine function seems doesn't work, and I cannot give a rigorous proof of it. Any suggestion, idea, or comment is welcome, thanks! How does passive perception work Total noob question, but the passive perception is confusing. I don't understand how to calculate it or use it, and I need help. It is not unusual for an Ubuntu (or other distro with apt package management) user to encounter the error: user@box ~ $ sudo apt install x [sudo] password for user:  Reading package lists... Done Building dependency tree        Reading state information... Done Package x is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'x' has no installation candidate  There have been several questions asked concerning this on various StackExchange sites,for example  on AskUbuntu, but these are generally about how to obtain the specific package despite the error. I have found no package that is not found simply (though not always easily) by determining if it is still distributed, and under which repository if so, and ensuring that repository is in apt.sources, or the worst comes to the worst downloading a .deb or source to compile. So my question is more general, and although I am guessing it has a rather simple and therefore non-exciting answer I cannot think how to find it by conventional search engine methods, so I turn to AskUbuntu: Is there a command or option I can use to determine what package / which packages reference the missing package? Prove $ \forall c \in \mathbb{R^{+}}, \forall B \in \mathbb{N}, \exists n \in \mathbb{N}, (n \geq B) \wedge (\sqrt{2n} > c \ln(n+2)) $? Saleforce Too many future calls: 11 Undefined variable problem with PHP function Strange black shading. Cannot fully light mesh. (Cycles) Here is the viewport in material view.  The node setup is just a PNG texture into a diffuse shader.    And this is in rendered view.  I've tried using environmental lighting as well as a directional light, and while the lit parts become brighter/washed out, the darker parts stay dark.  Normals are correct and there is no z-fighting.  Ambient Occlusion is not enabled.  Changing to Flat shading makes it worse.    Update:  Any modifier that alters the mesh (bevel, subdivide, etc) make the problem go away instantly. I want to model this gun:  So I started to cut out the rough shapes from a cube (using the boolean modifier) Then I tried to clean up the geometry to be able to round the edges of the handguard.  But it does not work. When I try to bevel it like in the last pic top right it just gets really messy.  I think I took the wrong approach. How would you go about adding clean and workable geometry to such a piece and would you use the Bevel tool to create the round shapes? I want to prove the assertion:      The unique quadratic subfield of $\mathbb{Q}(\zeta_p)$ is $\mathbb{Q}(\sqrt{p})$ when $p \equiv 1 \pmod{4}$, respectively $\mathbb{Q}(\sqrt{-p})$ when $p \equiv 3 \pmod{4}$.   My first attempt is this. In $\mathbb{Z}[\zeta_p]$, $1-\zeta_p$ is prime and $$ p = \epsilon^{-1} (1-\zeta_p)^{p-1} $$ where $\epsilon$ is a unit.  Since $p$ is an odd prime, $(p-1)/2$ is an integer and  $$ \sqrt{\epsilon p } = (1-\zeta_p)^{(p-1)/2} $$ makes sense and belongs to $\mathbb{Z}[\zeta_p]$.    How do I deal with the $\epsilon$ under the square root?  I guess the condition on the congruence class of $p$ comes from that.  Is this even the right way to proceed?  Uniqueness is not clear to me either.  I thought about looking at the valuation $v_p$ on $\mathbb{Q}$, extending it to two possible quadratic extensions beneath $\mathbb{Q}(\zeta_p)$, then seeing how those have to extend to common valuations on $\mathbb{Q}(\zeta_p)$, but I didn't see how to make it work.  I would appreciate some help. How to prove that $\frac{x^2}{yz+2}+\frac{y^2}{zx+2}+\frac{z^2}{xy+2}\geq \frac{x+y+z}{3}$ holds for any $(x,y,z)\in[1,2]^3$ Prove that for $x,y,z\in [1,2]$ the following inequality holds: $$\frac{x^2}{yz+2}+\frac{y^2}{zx+2}+\frac{z^2}{xy+2}\geq \frac{x+y+z}{3}.$$ I tried to apply the Cauchy-Schwarz inequality or the power mean inequality, but my attempts were unsuccessfull, so I am asking for help. Show bounded and convex function on $\mathbb R$ is constant Could the change from an edit be displayed in a side-by-side display How can I recover data from a 2TB hard drive? I have a Western Digital 2TB External Hard Drive. I basically use it to keep all my movies and videos. Its file system is NTFS, and currently I'm using 1.4TB. One night I turn it on and copied a 4GB file and there was no problem. Then I tried to copy another 6GB file and Ubuntu throw the following error: "Input/output error". I tried to create a new folder with no luck. I still could read the disk an play a file, so I thought restarting the computer would solve the problem, but it didn't. The next time, Ubuntu didn't mount the disk.   After that I tried in another PC with Window 7. It throwed a message telling me: first, that the disk needs to be formatted, and second, a "Local Disk #: Is not accessible. Data error (cyclic redundancy check)". Here is when I started to worry. I tried to fix the disk with CHKDSK (chkdsk \r). After about 5 hours, it crashed with the following error: "An unspecified error occurred".  My guess to all this is that the disk is dying. :'(  Lastly I did one more thing. I installed GSmartControl on Ubuntu to see the SMART info and the attributes tab appears in red with the following line highlited:  ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE ... 197 Current_Pending_Sector  0x0032   197   197   000    Old_age   Always       -       977 ...   Just to check, I left the disk on for about 2 minutes and then refreshed the page, and the Current_Pending_Sector RAW_VALUE increased from 977 to 979. My guess is that sectors on the disk are dying. Am I right?  If every time I turn on the disk more sectors are going to die, I need to copy the data fast. I don't know if there is a solution on Windows, and I'm worried about the time that it could take to do it with the slowness of Windows. Basically my question is: How can I recover the data? (Or at least some of it). Is there any program on Ubuntu that can help me with this (If I'm still on time)?. My main concern is the size of the disk (2TB), so I think I would need at least another 2TB disk to copy to.  Any help would be appreciated. Accelerating electrons via microwaves In Synchrotrons I think they use microwaves to accelerate the electrons bundles that fly through-how does putting a microwave through a cavity accelerate an electron? I know that the Electric and Magnetic fields could and do have an effect on the electron, but if the radiation is moving parallel to the electron, wouldn't the force be perpendicular? Also, how exactly does the microwave radiation look in the vacuum chamber? Are the two ends constant nodes? Is there a reason why ls does not have a --zero or -0 option Loop-cut won't go all the way around Alright so I've seen some postings about loop cuts and done some research. I am very new to blender and modeling overall. I am trying to loop cut this concrete barrier. Now I'm following a tutorial and kind of did my own thing in some areas. I cleaned it up following some instructions in another answer here on stack exchange.  I can't for the life of me figure out why I can loop cut around the whole bottom:   ...but not the whole middle:   I see this marked as answered by another question. That question refers to ngons and inside faces. Now once again I'm totally new to this. I looked on the inside. I don't believe I have inside faces or any ngons by the terms I've read online in my research.  Here is a wireframe picture and the inside view:     Maybe I'm missing something the answers on other posts are saying. If so and you know what it is I'd be very appreciative of what it is. "A quarter past five" or simply "Quarter past five"? I usually say “It’s a quarter past” (for instance) “five”.  But I think I’ve heard (or read) “It’s quarter past ...”, too, with no indefinite article: is that correct?  Which is more common (if both constructions are in use)?  Is the omission of the article more colloquial (informal, popular, whatever)?  Is there a difference between British and American English?  Thank you very much.