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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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Select first row in each GROUP BY group?
... BY p.customer) y ON y.customer = x.customer
AND y.max_total = x.total
GROUP BY x.customer, x.total
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Why does calling a method in my derived class call the base class method?
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There's a difference between new and virtual/override.
You can imagine, that a class, when instantiated, is nothing more than a table of pointers, pointing to the actual implementation of its methods. The following image should visualize this pretty well:
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What's the difference between “squash” and “fixup” in Git/Git Extension?
...the commit log message begins with "squash! ..." (or "fixup!
..."), and there is a commit whose title begins with the same ...,
automatically modify the todo list of rebase -i so that the commit
marked for squashing comes right after the commit to be modified,
and change ...
Capturing Groups From a Grep RegEx
..._[0-9a-z]*"
for f in $files # unquoted in order to allow the glob to expand
do
if [[ $f =~ $regex ]]
then
name="${BASH_REMATCH[1]}"
echo "${name}.jpg" # concatenate strings
name="${name}.jpg" # same thing stored in a variable
else
echo "$f doesn't...
Will strlen be calculated multiple times if used in a loop condition?
...tion. If it might, then you'll need to either call strlen() each time, or handle it through more complicated logic.
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How can I fix WebStorm warning “Unresolved function or method” for “require” (Firefox Add-on SDK)
...project or enable Node.js Globals predefined library in Settings/Languages and Frameworks/JavaScript/Libraries.
(Edited settings path by @yurik)
In WebStorm 2016.x-2017.x: make sure that the Node.js Core library is enabled in Settings (Preferences) | Languages & Frameworks | Node.js and NPM
I...
How to make JavaScript execute after page load?
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Note that the last option is a better way to go since it is unobstrusive and is considered more standard.
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How do I specify new lines on Python, when writing on files?
...e a single '\n' instead, on all platforms." So what do you mean by "right" and what are the reasons for their and your comment?
– Yasen
Nov 22 '14 at 18:41
22
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Does PostgreSQL support “accent insensitive” collations?
...r now
This approach is more efficient as other solutions floating around, and safer.
Create an IMMUTABLE SQL wrapper function executing the two-parameter form with hard-wired schema-qualified function and dictionary.
Since nesting a non-immutable function would disable function inlining, base it o...