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How do I calculate the normal vector of a line segment?

...000/svg\"\u003e\u003cpath d=\"M46.1709 9.17788C46.1709 8.26454 46.2665 7.94324 47.1084 7.58816C47.4091 7.46349 47.7169 7.36433 48.0099 7.26993C48.9099 6.97997 49.672 6.73443 49.672 5.93063C49.672 5.22043 48.9832 4.61182 48.1414 4.61182C47.4335 4.61182 46.7256 4.91628 46.0943 5.50789C45.7307 4.9328 4...
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C# : 'is' keyword and checking for Not

... 32 @Frank it works because is has higher precedence relative to ==. The only reason you can't use !x is f is that it has less precedence than ...
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How to paste in a new line with vim?

I often have to paste some stuff on a new line in vim. What I usually do is: 14 Answers ...
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If table exists drop table then create it, if it does not exist just create it

...s case than not to cover, see locking note below). Second RENAME ... atomically replaces table definition, refer to MySQL manual for details. At last, DROP ... just cleans up the old table, obviously. Wrapping all statements with something like SELECT GET_LOCK('__upgrade', -1); ... DO RELEASE_LOCK...
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Test if a command outputs an empty string

...one want to use the -l switch which means "use a long listing format" when all you want is test if there is any output or not, anyway? So most of the answers here are simply incorrect. Second problem The second problem is that while some answers work fine (those that don't use ls -al or ls -Al bu...
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Rails migration for change column

...). If it starts with "add" or "remove" then the migration will be automatically populated with code to add or remove columns, which saves you writing that code yourself. – Alex Korban Oct 26 '11 at 19:35 ...
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Func delegate with no return type

All of the Func delegates return a value. What are the .NET delegates that can be used with methods that return void? 7 Ans...
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Define css class in django Forms

... The only sane solution, I must say. Thank you!. Python code, and especially in form's definition, is the last place to put stuff for styling - these definitely belong to the templates. – Boris Chervenkov Nov 12 '11 at 23:09 ...
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How can you do anything useful without mutable state?

...me, there are tons of state variables, beginning with the positions of all the characters, who tend to move around constantly. How can you possibly do anything useful without keeping track of changing values? If you're interested, here's a series of articles which describe game program...
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AddRange to a Collection

...erfectly reasonable. There is a List<T>.AddRange() method that basically does just this, but requires your collection to be a concrete List<T>. share | improve this answer | ...