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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...
Why shouldn't all functions be async by default?
...d now includes not just CPU computations but also some I/O? You'll need to convert the method to async but this would break API and all the callers up the stack would be needed to be updated as well (and they can even be different apps from different vendors). Or you'll need to add async version alo...
How to delete items from a dictionary while iterating over it?
...t.keys() returns an iterator not a list.
As pointed out in comments simply convert mydict.keys() to a list by list(mydict.keys()) and it should work.
A simple test in the console shows you cannot modify a dictionary while iterating over it:
>>> mydict = {'one': 1, 'two': 2, 'three': 3...
Missing Maven dependencies in Eclipse project
... FYI, I first had to right click on my project, go to Configure and "Convert to Maven project."
– duma
Jul 24 '14 at 16:10
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Is there a performance difference between a for loop and a for-each loop?
... The for-each loop, introduced in
release 1.5, gets rid of the clutter
and the opportunity for error by
hiding the iterator or index variable
completely. The resulting idiom
applies equally to collections and
arrays:
// The preferred idiom for iterating over collections and arrays
for (...
Setting Short Value Java
... There are suffixes for other types as well: d/D makes a double and f/F makes a float!
– Joachim Sauer
Feb 19 '10 at 8:48
6
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What is the best way to give a C# auto-property an initial value?
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In C# 5 and earlier, to give auto implemented properties an initial value, you have to do it in a constructor.
Since C# 6.0, you can specify initial value in-line. The syntax is:
public int X { get; set; } = x; // C# 6 or higher
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Can I “multiply” a string (in C#)?
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And it's not much more in .NET 3.5: String.Concat(Enumerable.Repeat("Hello", 4).ToArray())
– Mark Foreman
Sep 3 '12 at 0:54
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Last iteration of enhanced for loop in java
...e don't use "" + i, by the way - you don't really want concatenation here, and StringBuilder has a perfectly good append(int) overload.)
int[] array = {1, 2, 3...};
StringBuilder builder = new StringBuilder();
for (int i : array) {
if (builder.length() != 0) {
builder.append(",");
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Python, add trailing slash to directory string, os independently
...OS X, this returns the path unchanged; on case-insensitive filesystems, it converts the path to lowercase. On Windows, it also converts forward slashes to backward slashes.
Else you could look for something else on this page
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