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Why is SSE scalar sqrt(x) slower than rsqrt(x) * x?
I've been profiling some of our core math on an Intel Core Duo, and while looking at various approaches to square root I've noticed something odd: using the SSE scalar operations, it is faster to take a reciprocal square root and multiply it to get the sqrt, than it is to use the native sqrt opcode!...
When should we use intern method of String on String literals
...in String pool, otherwise a new string object will be added in String pool and the reference of this String is returned.
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Best way to test for a variable's existence in PHP; isset() is clearly broken
...l scope variables as well, on can do a $defined_vars = get_defined_vars(); and then test via array_key_exists('v', $defined_vars);.
– Henrik Opel
Sep 27 '10 at 16:01
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Should I implement __ne__ in terms of __eq__ in Python?
...legate to __ne__ on the other side, not self == other is (assuming the operand's __eq__ doesn't know how to compare the other operand) implicitly delegating to __eq__ from the other side, then inverting it. For weird types, e.g. the SQLAlchemy ORM's fields, this causes problems.
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When to use references vs. pointers
I understand the syntax and general semantics of pointers versus references, but how should I decide when it is more-or-less appropriate to use references or pointers in an API?
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NHibernate vs LINQ to SQL
...orld projects I wonder if anyone knows how these two complement each other and how much their functionalities overlap?
9 An...
How can I test https connections with Django as easily as I can non-https connections using 'runserv
I have an application that uses "secure" cookies and want to test it's functionality without needing to set up a complicated SSL enabled development server. Is there any way to do this as simply as I can test non-encrypted requests using ./manage.py runserver ?
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Difference between modes a, a+, w, w+, and r+ in built-in open function?
...tion, what is the exact difference between the modes w , a , w+ , a+ , and r+ ?
6 Answers
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How do I update an entity using spring-data-jpa?
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Identity of entities is defined by their primary keys. Since firstname and lastname are not parts of the primary key, you cannot tell JPA to treat Users with the same firstnames and lastnames as equal if they have different userIds.
So, if you want to update a User identified by its firstname a...
When should I use C++14 automatic return type deduction?
...11 raises similar questions: when to use return type deduction in lambdas, and when to use auto variables.
The traditional answer to the question in C and C++03 has been "across statement boundaries we make types explicit, within expressions they are usually implicit but we can make them explicit w...