I bought a model that has .obj, .fbx and .max formats. I use Mac, so I'm not able to use .max, so I decided to import .obj in Blender. After I imported the file, I saw that a part of it hidden as if there was a gray wall or a portal to another universe. It's hard to explain it, better check the gif:    I'm totally new to Blender, so I have no idea what it is.
I'm having an odd issue - When I try to zoom in on a detail using my MMB, the "camera" in the 3D view seems to be cutting off the exterior surface of my object and showing me the inside instead. I'd expect this behavior, but only when I was much more zoomed in.  If I zoom out a bit (one click on the scroll wheel) then I can see the exterior as I intend.  Is there any way to adjust this behavior?  Thanks!
What is known about $\mathcal C^\infty$ functions $\mathbb R\to\mathbb R$ that always take rationals to rationals? Are they all quotients of polynomials? If not, are there any that are bounded yet don't tend to a limit for $x\to +\infty$? If there are, then can we also require them to be analytic?  (This is basically just a random musing after I found myself using trigonometric functions twice in unrelated throwaway counterexamples. It struck me that it was kind of conceptual overkill to whip out a transcendental function for the purpose I needed: basically that it had to keep wiggling forever. I couldn't think of a nice non-trancendental function to do this job, however, and now wonder whether that is because they can't exist). I would like to count the number of unique selections from a column that contains multiple selections from a drop down list.  For example, column B3 contains,     Monday, Tuesday, Wednesday   The count function returns a value of 1 instead of 3 - is there any way to count the three days distinctly? Thank you!  Multiple selections from a drop down list was made possible using the VBA code from: Evaluate these infinite products $\prod_{n\geq 2}(1-\frac{1}{n^3})$ and $\prod_{n\geq 1}(1+\frac{1}{n^3})$ What is   $\prod\limits_{n\geq 2}(1-\frac{1}{n^3})=?$ $\prod\limits_{n\geq 1}(1+\frac{1}{n^3})=?$   I am sure about their convergence. But don't know about exact values. Know some bounds as well. For example first one is in interval (2/3,1) and second one is in (2,3). What role-playing games should I pick for an absolute beginner group? I read this set of stories in the 80's.  What I recall is this:  A planet where the ruling caste was made up of humanoid women.  These women would, as almost pubescent girls, go out into the wilderness with only a spear and attempt to kill an animal in a life or death struggle.  When it happened, they would burst open a DNA packet in themselves that caused them to rapidly mature, their skin to become bronze colored, and give them some kinds of other "powers", I think over fire.  They were called "Bahronas", I think.  The population of this planet was primitive, but they were in contact with an advanced humanoid species, I think of actual homo-sapiens, who were there observing and advising them.  The advanced species wasn't allowed to intervene, just advise and watch.  The main character was a castaway boy, crash landed on their planet and stranded.  He became friendly with the ruling family of Bahronas and entered their confidence.  We find out through the course of the story that he's been genetically engineered and is not a normal boy.  At some point, the advanced species notices him and explains that he is a clone of a famous explorer and a spy, and they explain that they won't do anything in front of him.  The central part of the story is something of a blur, but, the final part of the story is told in a dramatically different style and shifts to a planet populated by catlike creatures who live in boughs of silk scarves, some of which sing.  THey are recording devices which play back the songs.  On this planet, there is another silk scarf, a white one, which doesn't play a song at all.  The cat creatures are greatly disturbed by it when they hear it's message, which they don't understand.  The narrator then goes on to say that it's a spoken word recording, made by the explorer which the boy was a clone of, explaining that he is captured and held hostage on the planet which makes the scarves, and forced to help make them (I think.) Object Positions Reset On Blender Load So I am attempting to make a modular environment in Blender, so I'm modeling many pieces in one scene to make sure they all match up properly before separating them out.  However, whenever I restart Blender after saving and closing it, many of my grouped objects (and their subobjects) have positions reset NOT to where I placed them.  For example, take a look at this:   Here you can see that the door pieces are in the "open" state, when I left them closed AND the "column" for the wall on the left has been moved from being flush with the wall (on the side) to being inside it.  It appears to be trying to move all of the objects to 0,0,0 which is what is messing this up. I'm not sure if it's an object hierarchy problem, but here is my hierarchy if anyone has ideas there:  Wall_Normal (parent)   Wall_Normal_Column (child)   Empty Axis Object (parent)   Door_Left (child a) Door_Right (child b)   Is there a reason why object positions (and their relative subobjects) aren't being saved? When is it okay to exceed the absolute maximum rating on a part? Proofs involving $ (A\setminus B) \cup (A \cap B)$ Give short arguments for each part below to complete the reasoning. Please do not use Venn diagrams.     a. Prove that $A = (A\setminus B) \cup (A \cap B)$.   (Hint: You should prove that $(A\setminus B)\cup (A\cap B) \subseteq A$ and vice-versa)      b. Prove that $(A \setminus B) \cap (A \cap B) = \emptyset$   (Hint: Try a proof by contradiction for this statement.).    I'm not too sure exactly where to start on this. Both statements make sense logically, but I don't know how exactly to prove them. Can anyone point me in the right direction? The change in energy of an object can be determined by the work equation, where work is the change in energy:  $$ W = F \cdot d $$  I conceptualize the transfer of energy as simply a series of small "packets" of energy being transferred at every Planck length. These small "packets" of energy add up to the total energy transferred (i.e. work). I'm not sure if this conceptualization is correct, so correct me if I am wrong.  However, it makes me wonder why the amount of energy transferred is dependent on distance and not time.  $$ m_1 = 10~kg \\ m_2 = 20~kg \\ W_1 = (10~N)\cdot(5~m) = 50~J \\ W_2 = (10~N)\cdot(5~m) = 50~J \\ W_1 = W_2 \\ t_1 \neq t_2 $$  If I apply a constant force on an object, why isn't the energy transferred at a constant rate with respect to time? The energy transfer rate varies dependent on how long it takes to cover the set distance.  In other words: why is the energy transferred consistent per unit of distance, and not per unit of time? Change elements on different positions within a list Mankind prepares for a war with aliens by warring among itself I am looking for the title or author of a atory I read back in the 90's, no idea when it was written. The plot goes something like this: Humanity has gained access to space travel and sends 9 or 12 survey ships towards galactic center, only 1 returns with stories of an enemy so rapacious that humanity starts preparing for war. After a long time, the enemy hasn't shown up and people begin to doubt the need to keep building for war. The government engineers a plan to turn the core systems against the fringe worlds and start warring amongst ourselves so that we may be prepared for when the real enemy shows up.  Written with the focus on one spaceship captain battling in our own internal war. I am using a 36 V battey pack (10s 2.5 A each cell 3.6V.) Its maximum voltage is 42 V. I am using a STM32 microcontroller whose input is 3.3 V.  I am designing a PCB in which the power supply is drawn from the battery pack (42 V.) I would like to power the STM32 microcontroller from the battery pack power supply.  I would like to regulate 42 to 3.3 V so that I can power my STM32 microcontroller.   Which method is best to convert it either using regulator or buck converter based on the pcb designing?  Battery Specification: 10s1p   Battery pack nominal voltage: 36 V Battery pack maximum voltage: 42 V Battery pack current: 2500 mAh   Microcontroller specfication: STM32F401RCT6   Supply voltage: 3.3 to 3.6 V Supply current: 100 to 160 mA     Which method or component is best to regulate 42 V so that I can power my microcontroller with 3.3 V? Best way to select a subset of items in a long list One of our clients wants us to build a web application to share information about the magazines he publishes. Each edition of a magazine contains a variable amount of advertisers. These advertisers come from a central pool of advertisers. This pool contains (at the moment) about 150 advertisers. Each edition of a magazine contains a subset (about 70-80) of these advertisers.  Our client wants us to come up with a way for him to add 70-80 advertisers from this list of 150 to an edition of a magazine. It needs to be as fast as possible, as easy as possible and as intuitive as possible.  What would be an ideal solution here? I was thinking about something in the lines of the image below.   List of available advertisers. List of selected advertisers. Advertisers have a delete button. Textbox with auto-suggest for advertisers in the list on the left. &lt;Enter> removes the advertiser from the left list and adds it to the right one. Textbox gets cleared and remains focus.   My colleagues suggested drag-and-drop or just one list with a checkbox for each advertiser, but those approaches force the user to do a lot of searching and clicking. With my approach the user can just keep on typing.  Any other suggestions for this situation? I've been very into acoustics lately, specifically the harmonic series. I find it fascinating how the harmonic series works as a sort of guideline to harmony, and how we base tuning systems on trying to estimate the intervals from the harmonic series.  As you've probably gathered already, I know close to nothing about acoustics. But I would love an acoustic textbook that's suitable for dummies like myself. Assume that $A$ is an $n\times n$  real matrix, i.e. $$A^T=-A.$$  Since $\det(A-\lambda I)=\det(A^T-\lambda I)$, $A$ and $A^T$ have the same eigenvalues. On the other hand, $A^T$ and $-A$ also have the same eigenvalues. Thus if $\lambda$ is an eigenvalue of $A$, so is $-\lambda$. If $n$ is odd, $\lambda = 0 $ is an eigenvalue.  A curious search in Google returns  the nonzero eigenvalues of $A$ are all pure imaginary and thus are of the form $iλ_1, −iλ_1, iλ_2, −iλ_2,$ … where each of the $λ_k$ are real.   Here is my question:     How can I prove the fact that "the nonzero eigenvalues of $A$ are all pure imaginary"? How do I get the deformed coordinate of a vertex with Python? How might someone find the deformed coordinate via Python or otherwise when using a subdivision modifier with the 'show on cage' option?  For example, a subdivided cube with cage enabled and a vertex selected shows the location of the vertex at 1,1,1 but when manually placing the cursor near on the surface it is closer to .5,.5,.5  I know the vertex location needs to be at its non-deformed location for subdivision to even work but would like to get more accurate point locations at the surface without having to apply to mesh. I have a Nexus 7 (2013) and a Moto X (2014) running Lollipop. On both of these, if I get a heads-up notification (i.e., those that show up on top of the screen when the device is unlocked) and swipe down on it with 2 fingers, it 'breaks' further heads-up notifications:   I can't tap on them to open the responsible app For, e.g., an incoming phone call with 'answer' and 'dismiss' buttons, tapping the buttons does nothing. I can't answer phone calls anymore!   I can still swipe to the side to dismiss the notifications, and they still disappear on their own after a few seconds. I haven't been able to find a way to get the correct behavior back aside from a restart.  Yeah, the obvious workaround is to not two-finger swipe on them, but it's second nature as that same gesture expands notifications in other contexts.  I'm guessing the problem is generic, but I've triggered it on Hangouts and Phone notifications.  Do others experience the same thing? Any known 'fixes' aside from restarting? Showing diffeomorphism between $S^1 \subset \mathbb{R}^2$ and $\mathbb{RP}^1$ I am trying to construct a diffeomorphism between $S^1 = \{x^2 + y^2 = 1; x,y \in \mathbb{R}\}$ with subspace topology and $\mathbb{R P}^1 = \{[x,y]: x,y \in \mathbb{R}; x \vee y \not = 0  \}$ with quotient topology and I am a little stuck.  I have shown that both are smooth manifolds, and I used stereographic projection for $S^1$, but now I am runing into trouble when I give the homeomorphism between $S^1$ and $\mathbb{RP}^1$ as the map that takes a line in $\mathbb{RP}^1$ to the point in $S^1$ that you get when letting the parallel line go through the respective pole used in the stereographic projection.   If I use the south and north poles I get a potential homeomorphism, but I cannot capture the horizontal line in my image, but when I pick say north and east then my map is not well defined as I get different lines for the same point in $S^1$. Can somebody give me a hint how to make this construction work, or is it better to move to a different representation of $S^1$ ? After the events on Miller's planet, it seems to come as a revelation to Brand that     Miller had only landed a couple hours ago, and died a few minutes ago.   The crew of the Endurance, even when they were back at NASA headquarters, had all the information they needed to figure out the time dilation and how long Miller had been on the planet. As such, they must have known that     Miller, even in the best case, would have only had a couple hours worth of data.   Why use all those resources (fuel and time) just for that? How to prove Fibonacci sequence with matrices?