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How does C compute sin() and other math functions?
...at book, you can decide if you have a hardware adder, multiplier, divider, etc, and decide which operations are fastest. e.g. If you had a really fast divider, the fastest way to calculate sine might be P1(x)/P2(x) where P1, P2 are Chebyshev polynomials. Without the fast divider, it might be just P(...
Performance difference for control structures 'for' and 'foreach' in C#
...get:
list[0]; // head
list[1]; // head.Next
list[2]; // head.Next.Next
// etc.
When you call GetEnumerator (implicitly using the forach-syntax), you'll get an IEnumerator object that has a pointer to the head node. Each time you call MoveNext, that pointer is moved to the next node, like so:
IEn...
JPA: How to have one-to-many relation of the same Entity type
... Collection<A> children;
// Getters, Setters, serialVersionUID, etc...
}
Here's a rough main() method that persists three such entities:
public static void main(String[] args) {
EntityManager em = ... // from EntityManagerFactory, injection, etc.
em.getTransaction().begin();
...
C++ auto keyword. Why is it magic?
...w people still write code for MS-DOS using compilers from Borland, Watcom, etc., that haven't seen significant upgrades in decades). If you're using a reasonably current version of any of the mainstream compilers, there's no reason to avoid it at all though.
...
Why would iterating over a List be faster than indexing through it?
...inter to the next element:
head -> item1 -> item2 -> item3 -> etc.
To access item3, you can see clearly that you need to walk from the head through every node until you reach item3, since you cannot jump directly.
Thus, if I wanted to print the value of each element, if I write this:...
HTML table with fixed headers?
...es.
Four lines of code.
Works for all configurations (table-layout: fixed, etc.).
document.getElementById("wrap").addEventListener("scroll", function(){
var translate = "translate(0,"+this.scrollTop+"px)";
this.querySelector("thead").style.transform = translate;
});
Support for CSS transfo...
Declaring variables inside loops, good practice or bad practice?
...ler to decide, based on what's best for the platform, optimization levels, etc. An ordinary int/float inside a loop will usually be placed on the stack. A compiler can certainly move that outside of the loop and reuse the storage if there is an optimization in doing that. For practical purposes, thi...
What's the difference between the atomic and nonatomic attributes?
... Given that any thread-safe code will be doing its own locking etc, when would you want to use atomic property accessors? I'm having trouble thinking of a good example.
– Daniel Dickison
May 24 '11 at 20:00
...
How do I find where an exception was thrown in C++?
...acro like:
#define THROW(exceptionClass, message) throw exceptionClass(__FILE__, __LINE__, (message) )
...and it will give you the location where the exception is thrown (admittedly not the stack trace). It's necessary for you to derive your exceptions from some base class that takes the above ...
Scheduling recurring task in Android
...n is not currently running. For normal timing operations (ticks, timeouts, etc) it is easier and much more efficient to use Handler.
Timer
timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
synchronized public void run() {
\\ here your todo;
}
...