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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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How to see which plugins are making Vim slow?
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If it's not clear, the resulting profile.log is a file in your Vim session's current directory.
– Micah Smith
May 10 '16 at 23:13
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Difference between Key, Primary Key, Unique Key and Index in MySQL
...imary key is a column, or a combination of columns, that can uniquely identify a row. It is a special case of unique key. A table can have at most one primary key, but more than one unique key. When you specify a unique key on a column, no two distinct rows in a table can have the same value.
Also ...
Programmatically fire button click event?
...nswer, but more flexible as it'll keep track of the buttons actual actions if you change them or add more than one.
[button sendActionsForControlEvents:UIControlEventTouchUpInside];
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An example of how to use getopts in bash
... ;;
*)
usage
;;
esac
done
shift $((OPTIND-1))
if [ -z "${s}" ] || [ -z "${p}" ]; then
usage
fi
echo "s = ${s}"
echo "p = ${p}"
Example runs:
$ ./myscript.sh
Usage: ./myscript.sh [-s <45|90>] [-p <string>]
$ ./myscript.sh -h
Usage: ...
What 'sensitive information' could be disclosed when setting JsonRequestBehavior to AllowGet
.../User/GetUser/32
which returns a JSON response:
{ "Name": "John Doe" }
If this method accepts only POST requests, then the content will only be returned to the browser if an AJAX request is made to http://www.example.com/User/GetUser/32 using the POST method. Note that unless you have implemente...
How to count the number of files in a directory using Python
...s.listdir() will be slightly more efficient than using glob.glob. To test if a filename is an ordinary file (and not a directory or other entity), use os.path.isfile():
import os, os.path
# simple version for working with CWD
print len([name for name in os.listdir('.') if os.path.isfile(name)])
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Unnecessary curly braces in C++?
... can hold on to some shared resource for a shorter duration than you would if you grabbed it at the start of the method.
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How to get the seconds since epoch from the time + date output of gmtime()?
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If you got here because a search engine told you this is how to get the Unix timestamp, stop reading this answer. Scroll down one.
If you want to reverse time.gmtime(), you want calendar.timegm().
>>> calendar.time...
Ruby Regexp group matching, assign variables on 1 line
...Rails"
p two #=> ":"
p three #=> " This is a test"
Be aware that if no match is found, String#match will return nil, so something like this might work better:
if match = string.match(/(^.*)(:)(.*)/i)
one, two, three = match.captures
end
Although scan does make little sense for this. I...