I have been experimenting with 2D Simplex noise for a mini-project and while I cannot say I understand the maths behind it, I begin to feel quite confident with how I can manipulate it to get different types of output.  While noise generation/algorithms/manipulation are quite easy to find, I am having trouble finding any good resources on the next step, i.e. placing 2D tiles based on the noise output (for the purpose of making some kind of 2D terrain).  I realize a crude and simple way would be to just loop through my array and place a tile on every coordinate where the noise value is above a certain point, but the output would look very rough, tiles would be overlapping each other, etc.  Does anyone have any good resources or information to share on this subject?  Thanks,
I am programming a tile based game and I have some basic tiles (grass, dirt, etc..), but I can't figure out how to make good random map generation, because when I do some really random selection, if the tile should be grass/dirt, I get this:    I understand why this is happening, but what I want is to create some random continuous areas of grass or dirt. Something that would make more sense, like this:
How to demystify the axioms of propositional logic? How might I go about getting some intuition on the typical axiom schemes given for propositional logic? They seem rather mysterious at first glance.  For example, these are taken from:    $\phi \to \phi$ $\phi \to \left( \psi \to \phi \right)$ $\left ( \phi \to ( \psi \rightarrow \xi \right)) \to \left( \left( \phi \to \psi \right) \to  \left( \phi \to \xi \right) \right)$ $\left ( \lnot \phi \to \lnot \psi \right) \to \left( \psi \to \phi \right)$ I know that big O is used to describe the upper bound of a function, so doesn't this mean that if the upper bounds f and g are the same, they are the same function? If this is the case, then we can say that  f ∈ Θ(g) because if that were not the case, then the two upper bounds would not be the same and thus one would out grow the other. Is this correct? What's the right way to represent phone numbers? How to use Alt+Shift to switch keyboard layouts? I recently upgraded to Ubuntu 13.10, with the new keyboard handling system. The little "switch keyboard" option does not let me set it to Alt+Shift. How can I get this keyboard binding, as I have absolutely no interest in using the Mac-esque Super+Space combo? Please explain this put option How many $4$ digit even numbers have all $4$ digits distinct ?   This question has been asked if we replace even with positive.   I was solving this Problem like: For first position $1-9$ (No $0$) for next $0-9$ (leaving out the digit which has been choose) for next $0-9$ (leaving out $2$ digits), but on last digit I get stuck. From what I should choose. Will it be $0, 2, 4, 6, 8$, because number needs to be even? How should I solve it? As a grad student, I just find it tremendously frustrating when emails are ignored by faculty (both at my institution and at other places). Is this acceptable? I'd be content with a simple response with one line along the lines of "I have read this email and am busy right now, will respond in X days when I can write a more detailed email." I understand that, as a first year student in my field, I'm not really in a position to request anything of anyone, but it just seems like common decency.  Instead, I never hear back, as if my email has been jettisoned off into oblivion. Loading D3.js data from a simple JSON string Prove that if $a$ and $b$ are odd, coprime numbers, then $\gcd(2^a +1, 2^b +1) = 3$ Prove that if $a$ and $b$ are odd, coprime numbers, then $\gcd(2^a +1, 2^b +1) = 3$.   I was thinking among the lines of:  Since $a$ and $b$ are coprime numbers, $\gcd(a,b)=1$. Then there exist integers $x$ and $y$ such that, $ax+by=1$.   Then, $a=(1-by)/x$, $b=(1-ax)/y$  So if I write $2^a+1$ as:  $2^{(1-by)/x}+1$  Then can I say that the above expression is equivalent to 0 (mod 3)? Can the cometd library be used in Salesforce to listen to external buses? I'll confess up front that my knowledge of event architecture is limited:  Can the cometd library that we can use to listen for Streaming API and Platform Events also be used to listen to external (i.e. non-Salesforce) event buses?  We're hoping to make Salesforce a subscriber to replace polling integrations through the REST API. What methods of ‘clearfix’ can I use? Lost my APFS partition after using EaseUS partition manager on Bootcamp I used macOS mojave(APFS partition) and Windows10(Bootcamp). And I tried to expand Bootcamp partition with moving Windows OEM partition by EaseUS partition master in windows. After this, I can’t find APFS partition installed macOS.  I use MacBook Pro 2016.  I think “disk0s2” was APFS partition, but now it is “Windows Recovery” partition.  Do you have any ideas to solve this? (I am Japanese, so I'm sorry for my poor English)  I tried “gpt show” and “diskutil list” on macOS Recovery   Additional information  I tried dd if=/dev/disk0s2 count=1 bs=512 command in a Terminal app of macOS Utility from network boot, and the terminal says,  -bash-3.2# dd if=/dev/disk0s2 count=1 bs=512 | vis -c 1+0 records in 1+0 records out 512 bytes transferred in 0.005472 secs (93568 bytes/sec) )us??-ҵ?\^A\0\0\0\0\0\0\0?\M^F\^Z\0\0\0\0\0\^A\0\0\M^@\0\0\0\0NXSB\0\^P\0\0?\M^B?\^B\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\^B\0\0\0\0\0\0\0"\^R???\M^_@}\M^Bvy57 ?(h?8\0\0\0\0\0?\M^F\^Z\0\0\0\0\0\^X\^A\0\0 l\0\0?\M^J\0\0\0\0\0\0\^R\r\0\0\0\0\0\0\a\0\0\0004*\0\0\^E\0\0\0\^B\0\0\0\^S*\0\0!\0\0\0\M^Qr8\0\0\0\0\0\M^U?\b\0\0\0\0\0\^A\^D\0\0\0\0\0\0\0\0\0\0d\0\0\0\^C\^D\0\0\0\0\0\0\M^T\M^N\^A\0\0\0\0\0\M^V\M^N\^A\0\0\0\0\0?0\^B\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0-bash-3.2#   . Is there an efficient way to copy text from a PDF without the line breaks? how to show image in table cell through json parsing How do I disable "Workspace dock" (a bottom panel with the list of open windows and a workspace indicator-cum-switcher), the one that is over "Plank" in the screenshot below?    I'm using Ubuntu 17.10. Ubuntu non LTS to LTS in the future Prove: $$ (a+b)^\frac{1}{n} \le a^\frac{1}{n} + b^\frac{1}{n}, \qquad \forall n \in \mathbb{N} $$ I have have tried using the triangle inequlity $ |a + b| \le |a| + |b| $,  without any success. SQLite - UPSERT *not* INSERT or REPLACE Is there some clever way to do this in SQLite that I have not thought of? Basically I want to update three out of four columns if the record exists, If it does not exists I want to INSERT the record with the default (NUL) value for the fourth column. The ID is a primary key so there will only ever be one record to UPSERT. (I am trying to avoid the overhead of SELECT in order to determine if I need to UPDATE or INSERT obviously) Suggestions?  I cannot confirm that Syntax on the SQLite site for TABLE CREATE. I have not built a demo to test it, but it doesn't seem to be supported. If it was, I have three columns so it would actually look like: CREATE TABLE table1(      id INTEGER PRIMARY KEY ON CONFLICT REPLACE,      Blob1 BLOB ON CONFLICT REPLACE,      Blob2 BLOB ON CONFLICT REPLACE,      Blob3 BLOB  );  but the first two blobs will not cause a conflict, only the ID would So I assume Blob1 and Blob2 would not be replaced (as desired)  UPDATEs in SQLite when binding data are a complete transaction, meaning Each sent row to be updated requires:  Prepare/Bind/Step/Finalize statements unlike the INSERT which allows the use of the reset function The life of a statement object goes something like this:  Create the object using sqlite3_prepare_v2() Bind values to host parameters using sqlite3_bind_ interfaces. Run the SQL by calling sqlite3_step() Reset the statement using sqlite3_reset() then go back to step 2 and repeat. Destroy the statement object using sqlite3_finalize().  UPDATE I am guessing is slow compared to INSERT, but how does it compare to SELECT using the Primary key? Perhaps I should use the select to read the 4th column (Blob3) and then use REPLACE to write a new record blending the original 4th Column with the new data for the first 3 columns? Which novel involves vampires, burning satellites, space travel, and body modification? About a decade ago, I encountered a novel or a novella that I cannot locate.   The setting was Earth, about one century into the future.  I remember vampires and a mesh of satellites around the Earth that were burning up in the atmosphere.  This motivated a mission to deep space to find the intelligence responsible for the satellites.  Most of the novel focused on the crew of the mission &mdash; I recall that they were not "standard" humans.  They had modifications to their minds and bodies, possibly for the mission.  At the time, I had gone on a binge, reading many short stories, novellas, and novels in quick succession.  I fear that I might be combining several stories into one, especially the vampires and the deep-space first-contact mission, and so I am fully prepared for an answer of the form, "No such story exists."  Any assistance would be greatly appreciated. Why no ooVoo on ubuntu?