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Is gcc std::unordered_map implementation slow? If so - why?
... found the reason: it is a Problem of gcc-4.7!!
With gcc-4.7
inserts: 37728
get : 2985
With gcc-4.6
inserts: 2531
get : 1565
So std::unordered_map in gcc-4.7 is broken (or my installation, which is an installation of gcc-4.7.0 on Ubuntu - and another installation which is gcc 4.7.1 on d...
Why does C++ rand() seem to generate only numbers of the same order of magnitude?
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There are only 3% of numbers between 1 and 230 which are NOT between 225 and 230. So, this sounds pretty normal :)
Because 225 / 230 = 2-5 = 1/32 = 0.03125 = 3.125%
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arrayfun can be significantly slower than an explicit loop in matlab. Why?
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2 Answers
2
Active
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Error TF30063: You are not authorized to access … \DefaultCollection
...view (Team Foundation Service) with one of my projects with Visual Studio 2012. I'm also using an on-premises TFS server with most of my projects. When I use my on-premises TFS after using TFS preview and go back to using TFS preview, I get this error:
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Why is there huge performance hit in 2048x2048 versus 2047x2047 array multiplication?
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This probably has do with conflicts in your L2 cache.
Cache misses on matice1 are not the problem because they are accessed sequentially.
However for matice2 if a full column fits in L2 (i.e when you access matice2[0, 0], matice2[1, 0], matice2[2, 0] ... etc, nothing g...
Add missing dates to pandas dataframe
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270
You could use Series.reindex:
import pandas as pd
idx = pd.date_range('09-01-2013', '09-30-2...
Python: avoid new line with print command [duplicate]
... printed:
print("Nope, that is not a two. That is a", end="")
In Python 2.x, you can use a trailing comma:
print "this should be",
print "on the same line"
You don't need this to simply print a variable, though:
print "Nope, that is not a two. That is a", x
Note that the trailing comma stil...
Benefits of inline functions in C++?
... situation like this making a detectable difference:
inline int aplusb_pow2(int a, int b) {
return (a + b)*(a + b) ;
}
for(int a = 0; a < 900000; ++a)
for(int b = 0; b < 900000; ++b)
aplusb_pow2(a, b);
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How to replace four spaces with a tab in Sublime Text 2?
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642
Bottom right hand corner on the status bar, click Spaces: N (or Tab Width: N, where N is an inte...
Is False == 0 and True == 1 an implementation detail or is it guaranteed by the language?
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In Python 2.x this is not guaranteed as it is possible for True and False to be reassigned. However, even if this happens, boolean True and boolean False are still properly returned for comparisons.
In Python 3.x True and False are k...