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可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: As you know, the first two are AVX-specific intrinsics and the second is a SSE4.1 intrinsic. Both sets of intrinsics can be used to check for equality of 2 floating-point vectors. My specific use case is: _mm_cmpeq_ps or _mm_cmpeq_pd , followed by _mm_testc_ps or _mm_testc_pd on the result, with an appropriate mask But AVX provides equivalents for "legacy" intrinsics, so I might be able to use _mm_testc_si128 , after a cast of the result to __m128i . My questions are, which of the two use cases results in better performance and where I can

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I know many people encountered this error before but I couldn't find the solution to my problem. I have a URL that I want to normalize: url = u"http://www.dgzfp.de/Dienste/Fachbeitr%C3%A4ge.aspx?EntryId=267&Page=5" scheme, host_port, path, query, fragment = urlsplit(url) path = urllib.unquote(path) path = urllib.quote(path,safe="%/") This gives an error message: /usr/lib64/python2.6/urllib.py:1236: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal res = map(safe_map._

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Is it guaranteed by the C++ standard that if I have two pointers of the same type whose value is equal to nullptr, that the difference between those pointers is equal to 0? In a pseudo-mathematical notation, does the following predicate hold true? ForAll x ForAll y (x == nullptr)^(y == nullptr) -> (x - y == 0) The simplest code example I can think of being: int* x = nullptr; int* y = nullptr; assert(x - y == 0); I suppose this boils down to: is it possible to have a valid implementation of the C++ standard for which there are multiple bit

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: What would be the most efficient way to compare two double or two float values? Simply doing this is not correct: bool CompareDoubles1 (double A, double B) { return A == B; } But something like: bool CompareDoubles2 (double A, double B) { diff = A - B; return (diff < EPSILON) && (-diff < EPSILON); } Seems to waste processing. Does anyone know a smarter float comparer? 回答1: Be extremely careful using any of the other suggestions. It all depends on context. I have spent a long time tracing a bugs in a system that presumed a==b if |a-b|<epsilon

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: Assuming we have a polygon coordinates as polygon = [(x1, y1), (x2, y2), ...], the following code displays the polygon: import matplotlib . pyplot as plt plt . fill (* zip (* polygon )) plt . show () By default it is trying to adjust the aspect ratio so that the polygon (or whatever other diagram) fits inside the window, and automatically changing it so that it fits even after resizing. Which is great in many cases, except when you are trying to estimate visually if the image is distorted. How to fix the aspect ratio to be strictly

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: This question already has an answer here: What is the difference between operator “=” and “==” in Bash? 2 answers In bash , what's the difference, if any, between the equal and double equal test operators? [[ "a" = "a" ]] && echo equal || echo not-equal [[ "a" == "a" ]] && echo equal || echo not-equal [[ "a" = "b" ]] && echo equal || echo not-equal [[ "a" == "b" ]] && echo equal || echo not-equal results in: equal equal not-equal not-equal 回答1: There's no difference, == is a synonym for = (for the C/C++ people, I assume). See here , for

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Could someone please explain the following behavior in SQL? SELECT * FROM MyTable WHERE MyColumn != NULL (0 Results) SELECT * FROM MyTable WHERE MyColumn NULL (0 Results) SELECT * FROM MyTable WHERE MyColumn IS NOT NULL (568 Results) 回答1: is Standard SQL-92; != is its equivalent. Both evaluate for values, which NULL is not -- NULL is a placeholder to say there is the absence of a value. Which is why you can only use IS NULL / IS NOT NULL as predicates for such situations. This behavior is not specific to SQL Server. All standards-compliant

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Boy, this one is really weird. I expect the following code to print 1990, but it prints 1989! $val = '$19.9'; $val = preg_replace('/[^\d.]/','',$val); $val = intval($val * 100); echo $val; Why on earth is this happening? Edit: and this code: $val = '$19.9'; $val = preg_replace('/[^\d.]/','',$val); echo $val . " "; $val = $val * 100; echo $val . " "; $val = intval($val); echo $val; Prints: 19.9 1990 1989 Why does intval(1990) equal 1989 ??? 回答1: This is a precision issue inherent to floating point numbers in PHP, and lots of other languages.

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Possible Duplicate: Javascript === vs == : Does it matter which “equal” operator I use? What is the difference between == and === in JavaScript? I have also seen != and !== operators. Are there more such operators? 回答1: === and !== are strict comparison operators: JavaScript has both strict and type-converting equality comparison. For strict equality the objects being compared must have the same type and: Two strings are strictly equal when they have the same sequence of characters, same length, and same characters in corresponding positions

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug. Is == bad? When should it and should it not be used? What's the difference? 回答1: == tests for reference equality (whether they are the same object). .equals() tests for value equality (whether they are logically "equal"). Objects.equals() checks for nulls before calling .equals() so you don't have to (available as of JDK7, also available in Guava ). Consequently, if you