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How do I calculate the normal vector of a line segment?
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if we define dx=x2-x1 and dy=y2-y1, then the normals are (-dy, dx) and (dy, -dx).
Note that no division is required, and so you're not risking dividing by zero.
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Build a Basic Python Iterator
...ator protocol, which basically means they provide two methods: __iter__() and __next__().
The __iter__ returns the iterator object and is implicitly called
at the start of loops.
The __next__() method returns the next value and is implicitly called at each loop increment. This method raises a...
How to silence output in a Bash script?
I have a program that outputs to stdout and would like to silence that output in a Bash script while piping to a file.
9 An...
How can I force WebKit to redraw/repaint to propagate style changes?
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I found some complicated suggestions and many simple ones that didn’t work, but a comment to one of them by Vasil Dinkov provided a simple solution to force a redraw/repaint that works just fine:
sel.style.display='none';
sel.offsetHeight; // no need to store...
bash HISTSIZE vs. HISTFILESIZE?
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Short answer:
HISTSIZE is the number of lines or commands that are stored in memory in a history list while your bash session is ongoing.
HISTFILESIZE is the number of lines or commands that (a) are allowed in the history file at startup time of a session, and (b) are stored i...
How to create NS_OPTIONS-style bitmask enumerations in Swift?
...C-style enumerations are imported as Swift enumerations. This makes sense, and since enumerations in Swift are readily provided as the enum value type it's easy to see how to create our own.
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Is there a JavaScript function that can pad a string to get to a determined length?
I am in need of a JavaScript function which can take a value and pad it to a given length (I need spaces, but anything would do). I found this:
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Iterator Loop vs index loop [duplicate]
I'm reviewing my knowledge on C++ and I've stumbled upon iterators. One thing I want to know is what makes them so special and I want to know why this:
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Position icons into circle
...can I position several <img> elements into a circle around another and have those elements all be clickable links as well? I want it to look like the picture below, but I have no idea how to achieve that effect.
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Trying to understand CMTime and CMTimeMake
1) CMTimeMake(1,10) means duration of 1 second and timescale of 10, or 10 frames per second. This means 1s duration of video with 10 frames?
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