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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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Dealing with multiple Python versions and PIP?
...This is the recommendation because it works across all versions of Python, and in all forms of virtualenv. For example:
# The system default python:
$ python -m pip install fish
# A virtualenv's python:
$ .env/bin/python -m pip install fish
# A specific version of python:
$ python-3.6 -m pip inst...
Valid to use (anchor tag) without href attribute?
I've been using Twitter Bootstrap to build a site, and a lot of its functionality depends on wrapping things in <a> , even if they're just going to execute Javascript. I've had problems with the href="#" tactic that Bootstrap's documentation recommends, so I was trying to find a different s...
What is the difference between Digest and Basic Authentication?
What is the difference between Digest and Basic Authentication ?
4 Answers
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Do AJAX requests retain PHP Session info?
If I had a user logged onto my site, having his id stored in $_SESSION , and from his browser he clicked a 'Save' button which would make an AJAX request to the server. Will his $_SESSION and cookies be retained in this request, and can I safely rely on the id being present in the $_SESSION ?
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Checking for an empty field with MySQL
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An empty field can be either an empty string or a NULL.
To handle both, use:
email > ''
which can benefit from the range access if you have lots of empty email record (both types) in your table.
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innerText vs innerHTML vs label vs text vs textContent vs outerText
...ile textContent gets the content of all elements, including <script> and <style> elements, the mostly equivalent IE-specific property, innerText, does not.
innerText is also aware of style and will not return the text of hidden elements, whereas textContent will.
As innerText is aware ...
How to request Administrator access inside a batch file
....bat file. The desired behavior is that when they right-click on the file and say Open, they will get one of those UAC dialogs that makes the screen go dark and forces them to answer whether they want to give the application permission to run as administrator. Instead, they are just seeing "Access...
Do python projects need a MANIFEST.in, and what should be in it?
...org, but that registration has lapsed) tells me to include doc/txt files and .py files are excluded in MANIFEST.in file
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What is referential transparency?
...branch of philosophy that analyzes natural language constructs, statements and arguments based on the methods of logic and mathematics. In other words, it is the closest subject outside computer science to what we call programming language semantics. The philosopher Willard Quine was responsible fo...