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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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Determine if a function exists in bash
...t tests which are executed from bash. Unit tests are initialized, executed and cleaned up in a bash script. This script usualy contains an init(), execute() and cleanup() functions. But they are not mandatory. I'd like to test if they are or are not defined.
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Is it good practice to use java.lang.String.intern()?
... that you're going to compare. It's easy to forget to intern() all strings and then you can get confusingly incorrect results. Also, for everyone's sake, please be sure to very clearly document that you're relying on the strings being internalized.
The second disadvantage if you decide to internali...
The Role Manager feature has not been enabled
...s from code instead of web.config? I tried putting it in Application_Start and it says This method can only be called during the application's pre-start initialization phase.
– Maslow
May 8 '13 at 15:17
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What is the $? (dollar question mark) variable in shell scripting? [duplicate]
I'm trying to learn shell scripting, and I need to understand someone else's code. What is the $? variable hold? I can't Google search the answer because they block punctuation characters.
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Admob Error in Eclipse for android:configChanges
Eclipse is giving me an error on the android:configChanges line in my AndroidManifest.xml:
7 Answers
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Why covariance and contravariance do not support value type
...or not.
You might want to read Eric Lippert's blog post on representation and identity for more on this topic in general.
EDIT: Having reread Eric's blog post myself, it's at least as much about identity as representation, although the two are linked. In particular:
This is why covariant and ...
Difference between Dictionary and Hashtable [duplicate]
What is the difference between Dictionary and Hashtable. How to decide which one to use?
7 Answers
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How is Racket different from Scheme?
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Racket is ultimately based on R5RS, and not R6RS and not a strict superset of either. I don't think it can be called 'Scheme' because it's not backwards compatible with any Scheme standard.
Most implementations offer extensions, but are otherwise backwards com...
Display HTML snippets in HTML
...ippets on a webpage without needing to replace each < with &lt; and > with &gt; ?
25 Answers
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