implementation

问题 How do you implement exponents in JQuery? I'm modifying this: $.fn.sumValues = function() { var sum = 0; this.each(function() { if ( $(this).is(':input') ) { var val = $(this).val(); } else { var val = $(this).text(); } sum += parseFloat( ('0' + val).replace(/[^0-9-\.]/g, ''), 10 ); }); return sum; and $(document).ready(function() { $('input.price').bind('keyup', function() { $('span.total').html( $('input.price').sumValues() ); }); to calculate a more complex formula of summations from user

问题 Firstly, I don't know what the most appropriate title for this question would be. Contender: "how to implement list.append in custom class". I have a class called Individual . Here's the relevant part of the class: from itertools import count class Individual: ID = count() def __init__(self, chromosomes): self.chromosomes = list(chromosomes) self.id = self.ID.next() Here's what I want to do with this class: Suppose I instantiate a new individual with no chromosomes: indiv = Individual([]) and

问题 Let's say we have the following code: (in a class that extends JPanel ): public void paintComponent(Graphics g) { g.drawImage(image, dx1, dy1, dx2, dy2, sx1, sy1, sx2, sy2, null); } If dx1 and dy1 are negative or dx2 and dy2 are larger than the width of the JPanel (in other words, part of the image will be off-screen), does drawImage() adjust what is rendered so that it only "pays attention to" the part visible on the JPanel ? I am curious about this because if I draw a very large image on

问题 I am trying to implement a customized error function in package neuralnet in R. Normally ’sse’ and ’ce’ which stand for the sum of squared errors and the cross-entropy are used to calculate error.Can anyone provide me details about how to implement own error function. Though the package says we can use customized error function,there is no help in the user Manuel about this. 回答1: I had the same Problem. This is the solution/help I received. You can use the usual definition of R functions

问题 I'm trying to resolve problem 14 of Project Euler (http://projecteuler.net/problem=14) and I hit a dead end using Haskell. Now, I know that the numbers may be small enough and I could do a brute force, but that isn't the purpose of my exercise. I am trying to memorize the intermediate results in a Map of type Map Integer (Bool, Integer) with the meaning of: - the first Integer (the key) holds the number - the Tuple (Bool, Interger) holds either (True, Length) or (False, Number) where Length =

问题 I have a C program that has n multiplications (single multiplication with n iterations) and I found another logic that has n/2 iterations of (1 multiplication + 2 additions). I know about the complexity that both are of O(n). but in terms of CPU cycles. which is faster ? 回答1: First of all follow Dietrich Epp's first advice - measuring is (at least for complex optimization problems) the only way to be sure. Now if you want to figure out why one is faster than the other, we can try. There are

问题 How is the ui:include tag implemented? Where can I find its implementation(source code)? 回答1: That's implementation dependent. In Mojarra, it's the com.sun.faces.facelets.tag.ui.IncludeHandler. In MyFaces, it's the org.apache.myfaces.view.facelets.tag.ui.IncludeHandler. 来源： https://stackoverflow.com/questions/10789373/the-class-behind-uiinclude-jsf-tag

问题 What's the difference between including a header file in a header file vs including it in a implementation file? This Ex: // test.h #include"globals.h" class Test { Test(); }; vs //test.cpp #include"globals.h" Test::Test() { } 回答1: The general principle is that you want to minimise dependencies wherever reasonably possible, so: if your interface (.h) references anything in a given header then that header needs to be #included in the interface (.h) if you only reference a given header in your

问题 I figure out I can have the implementation of parts of a class in a shared lib, as far as the symbols are loaded when used. myclass.h --- class C { void method(); } main.cpp --- #include "myclass.h" int main() { //dynamically load mylib.so using dlopen/dlsym/dlclose ... C *c = new C(); c->method(); delete c; } mylib.so compiled separately: ==== mylib.cpp --- #include "mylib.h" void C::method() { ... } This works fine. However once I finished using C::method(), I would like to unload it, so I

问题 How exactly is inheritance implemented in Java? For example, consider this: class A { public void foo() { System.out.print("A"); } } class B extends A { ... } class Test { public static void main(String[] args) { B test = new B(); test.foo(); // how is foo() called? } Below the line, would the compiler just dump the definition of A.foo() into the body of class B? Like class B extends A { ... public void foo() { System.out.print("A"); } } Or is foo somehow looked up in class A and called there