I installed a more recent version of hplip than the one distributed with 18.04, which made it impossible to install hp-plugin properly. So I want to get rid of the updated version and reinstall the version that came with 18.04.  I tried both sudo apt remove hplip and sudo apt purge hplip, then in both cases reinstalled with sudo apt install hplip.   But when I run hp-plugin after reinstall, the framework listed is still the updated version instead of the version from the Ubuntu repositories. Besides, the hp icon in the notification area is still there as well, so clearly not everything has been removed.  What can I do to either 1) completely remove all the components from the updated version or 2) install the version from the repositories in a way that will overwrite all the updated components?   In other words, how can I effectively completely replace the updated hp drivers and software with the ones from the repo? I'm getting so fed-up that I am considering reinstalling Ubuntu from scratch, which would be an humiliating defeat...  EDIT: I found a convoluted way to fix it (see in the comments below), but a shorter fix would have quite possibly been to simply add sudo apt install --reinstall hplip-gui in my reinstallation process. While the developer portal has a single package, ubuntu separates hplip and hplip-gui!
Let's assume that one has some modern HP printer and/or scanner which is not supported by HPLIP package from official repository. Currently Ubuntu versions have :  trusty (14.04LTS): 3.14.3-0ubuntu3.4 xenial (16.04LTS): 3.16.3+repack0-1 bionic (18.04LTS): 3.17.10+repack0-5 focal (20.04LTS): 3.20.3+dfsg0-2 groovy (20.10): 3.20.5+dfsg0-3build1 hirsute (21.04): 3.21.2+dfsg1-2   What can one do if printer is supported in newer version of HPLIP (checked this in )?
What is "summoning sickness" and how does it affect my creatures? Note: this is intended to be a canonical question about summoning sickness.  "Summoning sickness", broadly, is the rule that stops you from attacking or paying {T} costs with a creature that you just played. But how exactly does it work? How does it interact with other rules and effects?  For example, if I'm trying to figure out how a creature is affected:   Does the status matter (tapped/untapped, face down/face up, etc.)? What if it came into play, but I didn't cast it? What if it's a token? What if it was on the battlefield when my turn started, but it wasn't a creature? What if it stops being a creature? What if it's a creature and also another card type? What if it's a double-faced card that just transformed? What if it changes control? What if it's a copy of another creature? Which of the creature's activated abilities can I use? Are any of its other abilities affected? Can I tap the creature to pay a cost that is not a {T} cost?   (These examples are primarily taken from questions about summoning sickness that have already been asked on the site) Recently, I found this , that allows you to generate a 3D model from a 2D image.   It works very well and you can download an OBJ file. Vertex are colored and when I import it using Blender, I can't see any Vertex color.   Using Cycle (I prefer a internal solution if it exists) according to some answers I've found on Blender Stack Exchange, I patched some nodes : Attribute -> Diffuse BDSF -> Material Output.  Unfortunately, I can't get it works, the model stills black.    When I open the OBJ file, I see that color per vertex are there :  v 43.747554 107.000000 69.000000 0.470588 0.380392 0.309804 v 43.780163 115.000000 64.500000 0.427451 0.337255 0.266667 v 43.782527 107.000000 68.500000 0.470588 0.380392 0.309804 v 43.801902 115.000000 65.000000 0.427451 0.337255 0.266667 v 43.806461 107.000000 69.500000 0.470588 0.380392 0.309804 v 43.821703 115.000000 64.000000 0.427451 0.337255 0.266667 v 43.838352 108.000000 68.500000 0.466667 0.376471 0.305882 v 43.854670 106.000000 69.000000 0.482353 0.392157 0.321569 v 43.856176 108.000000 69.000000 0.466667 0.376471 0.305882 v 43.873876 106.000000 69.500000 0.482353 0.392157 0.321569 v 43.888855 110.000000 68.000000 0.466667 0.376471 0.305882 v 43.891471 109.000000 68.000000 0.466667 0.376471 0.305882 v 43.892733 110.000000 67.500000 0.466667 0.376471 0.305882 v 43.895170 108.000000 68.000000 0.466667 0.376471 0.305882 v 43.900904 109.000000 68.500000 0.466667 0.376471 0.305882 v 43.907584 107.000000 68.000000 0.470588 0.380392 0.309804 v 43.917898 115.000000 65.500000 0.427451 0.337255 0.266667 v 43.925000 111.000000 67.500000 0.454902 0.364706 0.294118   According to some answers here, Blender import more easily the vertex color of a PLY file so I tried to convert to PLY with two different sites :   1. meshconvert .com : Give me a 3.5 Mo file  2. greentoken.de/onlineconv : Give me a 2.3 Mo file  (Of course, if you know some other sites I could try, it interest me)  I guess that color data are lost with greentoken (not sure).   When I import the 3.5 Mo PLY file in blender, I need to be in textured display mode, then I think I see my vertex color value but in black &amp; white instead of RGB, that is weird. Anyway, I can't get it work  EDIT 1 : I opened PLY files and color vertex aren't there... I need to find a better converter   EDIT 2 : I tried www.ofoct.com/3d-model-file-for-3d-printer-converter it doens't take vertex color into account. In fact, in each PLY files I converted with the various sites here, there is a common line :      comment Created by Open Asset Import Library -    (v3.2.0)   (the version varies)  EDIT 3 : In fact it seems that model converted by Green token, keep the vertex color. That is weird because that's the smallest file :   ply format ascii 1.0 comment Created by Open Asset Import Library - http://assimp.sf.net (v3.1.187496374) element vertex 29793 property float x property float y property float z property float nx property float ny property float nz element face 59582 property list uint uint vertex_index end_header 82 103 6.37528 0.40963 0.0331735 0.911648 82 102 6.57043 0.272087 0.235193 0.933088 82.6603 103 6.5 -0.14071 0.043367 0.9891 82 103.935 6.5 0.201161 -0.136681 0.969976 81.5475 103 7 0.825371 0.0489484 0.562465 83 102 6.62244 -0.248588 0.147929 0.957247 83 103 6.56417 -0.411487 -0.0867124 0.907281 81.5819 104 7 0.787841 -0.0338904 0.614946 82 105 6.63886 0.0715144 -0.131383 0.988749 83 104 6.77321 -0.431167 -0.171652 0.885794 83.6781 102 7 -0.470137 0.061235 0.880467 83.6327 103 7 -0.543939 -0.0905203 0.834228 83 105 6.96709 -0.445324 -0.163091 0.880391 84 103 7.23724 -0.520118 -0.141377 0.842313 84 104 7.47775 -0.546517 -0.195833 0.814229 84 102 7.16782 -0.416323 -0.021798 0.908955 83.3508 101 7 -0.314426 0.156435 0.936304 84 101 7.22581 -0.280388 0.0301462 0.959413 84.9009 101 7.5 -0.339848 -0.0219793 0.940223 84.6939 102 7.5 -0.435242 -0.0925323 0.895546   As you can see, nx, ny and nz correspond to RGB values.. Has anyone used PostgreSQL with PostGIS successfully?   I am a semi-experienced ArcGIS user and want to build out a database and connect it to ArcCatalog.   I've scoured the internet for resources but nobody has really given a good walkthrough. Gamma Distribution out of sum of exponential random variables How to identify the process that's sending error messages to terminal? referring to Eqn. 1a) and 1b) in a sentence as eqn. (1) Error message on Terminal launch Now that the , I've been seeing tag-only suggested edits from 1500-rep users.  For example, one had the summary of 'burninating [tagThatWasRemoved]'.  It's very tempting to reject these as Too Minor, but I know that these users used to have a Retag privilege (and are obviously trying to participate in a burnination.)  What should we do for tag-only edits from high(er) rep users? TZInfo::DataSourceNotFound error starting Rails v4.1.0 server on Windows Why {are you / you are} making noise? I always get confused between these two sentences:     Why are you making noise?      Why you are making noise?   Could anyone put light in the differences between the two? Should form 'Continue' button be disabled if validation is incomplete? In forms we often see the 'continue' button inactive until all the required fields are complete:         &ndash; Wireframes created with   Is this actually a help to the user, or a hindrance?  I imagine the Pro for this is that it's a visual indicator to the user that they haven't finished filling in the form or dealing with errors (because even with inline validation a user won't be informed if they've never actually interacted with a field so won't show any errors for those at that point).  But then the main Con for this (which I've also seen borne out in usability testing) is that users will be confused why they can't click the button.  Is the pattern of disabling the Continue button until validation is complete actually providing a negative user experience? Arbitrary precision spline interpolation How to determine the amount of experience needed for leveling up Related questions under this topic might include:   How should I base how much experience points it takes to get to the next level? What factors are involved in this? How do I keep the player not entertained long enough till he levels up? How can I vary the way the player gets experience points? Zero dimensional points do not take up space, so then wouldn't everything in the universe be literally empty? Or is there something that I'm missing? On Linux can I keep a program running in background even after I disconnect? If I'm logged into a remote Linux machine, I know I can suspend a process (cntr-z) and move it to the background (bg 1) but if I disconnect from the machine, the process stops.  Is there a way I can leave it in the background and have it there when I log back in? This is a very long running process.  On Ubuntu, logged in via SSH. Suppose $a_n \ge 0$ for all natural numbers $\Bbb{N}$ and $\sum{a_n}$ converges. Is it necessarily true that $\sum{(a_n)^2}$ converges?  I think yes.  Clearly as $a_n \ge 0$ it follows $(a_1+a_2+\dots+a_n)^2 \ge a_1^2+a_2^2+\dots+a_n^2 \ge 0$ and so $(\sum_{n=1}^{\infty}{a_n})^2 \ge \sum_{n=1}^{\infty}{a_n^2} \ge 0$.  As we are told $\sum{a_n}$ converges to say $L$ where $L$ is a real number it follows $L^2 \ge \sum_{n=1}^{\infty}{a_n^2} \ge 0$ and so therefore $\sum{(a_n)^2}$ converges.  Is this correct? Catching access violation exceptions? Example  int *ptr; *ptr = 1000;   can I catch memory access violation exception using standard C++ without using any microsoft specific. How do I align an image to centre? How do I align an image to centre?  In a beamer presentation I have a 2-3 items on a slide followed by an image. The image is not wide enough to cover whole slide, so it leaves around 30% space from right. How do I adjust it to leave enough space on both sides?  \begin{frame} \frametitle{Outlook} \begin{itemize} \item apps \item apps \item apps \includegraphics[scale=0.3]{P2P}     \end{itemize} \end{frame} Is it possible to dynamically set Views' pager settings? Say for instance, you have a view that displays when viewing a certain node type, but you want the pager settings to be different for each individual node. I was thinking of making a CCK field like "pager setting" and then give it an integer option of x-y. But I don't know if it's possible to somehow dynamically plug that field into the Views' settings. Or is there another way to do this maybe? Making sense of principal component analysis, eigenvectors & eigenvalues In today's pattern recognition class my professor talked about PCA, eigenvectors and eigenvalues.   I understood the mathematics of it. If I'm asked to find eigenvalues etc. I'll do it correctly like a machine. But I didn't understand it. I didn't get the purpose of it. I didn't get the feel of it.        I strongly believe in the following quote:     You do not really understand something unless you can explain it to your grandmother. -- Albert Einstein   Well, I can't explain these concepts to a layman or grandma.   Why PCA, eigenvectors &amp; eigenvalues? What was the need for these concepts? How would you explain these to a layman?