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Why is transposing a matrix of 512x512 much slower than transposing a matrix of 513x513?
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The explanation comes from Agner Fog in Optimizing software in C++ and it reduces to how data is accessed and stored in the cache.
For terms and detailed info, see the wiki entry on caching, I'm gonna narrow it down here.
A cache is organized in sets and lines. At a time, only one set is u...
Position absolute but relative to parent
I have two divs inside another div, and I want to position one child div to the top right of the parent div, and the other child div to the bottom of the parent div using css. Ie, I want to use absolute positioning with the two child divs, but position them relative to the parent div rather than the...
How can I check if a scrollbar is visible?
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Note that on Macs the scrollbar floats over the content and disappears when not in use. On Windows it is always visible and takes up horizontal space. Therefor, just because content can be scrolled (which this function detects) does not mean that a scrollbar is necessarily present...
Convert string to variable name in JavaScript
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@WojciechBednarski: Don't confuse scope and context. this is context, what it points to depends on how the function is called. In JS, 50% of the time this is window unless you enable strict mode and this becomes undefined and will throw an error. Scope is something...
How do I create a round cornered UILabel on the iPhone?
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iOS 3.0 and later
iPhone OS 3.0 and later supports the cornerRadius property on the CALayer class. Every view has a CALayer instance that you can manipulate. This means you can get rounded corners in one line:
view.layer.cornerRadi...
When are C++ macros beneficial? [closed]
The C preprocessor is justifiably feared and shunned by the C++ community. In-lined functions, consts and templates are usually a safer and superior alternative to a #define .
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What's the safest way to iterate through the keys of a Perl hash?
...ng each may in some way have unintended side effects. So, is that true, and is one of the two following methods best, or is there a better way?
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Generic method multiple (OR) type constraint
...t types. That means you could just as well leave out the generic parameter and provide overloads.
– Botz3000
May 31 '12 at 13:00
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What does pylint's “Too few public methods” message mean
I'm running pylint on some code, and receiving the error "Too few public methods (0/2)". What does this message mean? The pylint docs are not helpful:
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Where in a virtualenv does the custom code go?
...en using virtualenv ? For instance, if I were building a WSGI application and created a virtualenv called foobar I would start with a directory structure like:
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