optimization

Image/"most resembling pixel" search optimization?

The situation: Let's say I have an image A, say, 512x512 pixels, and image B, 5x5 or 7x7 pixels. Both images are 24bit rgb, and B have 1bit alpha mask (so each pixel is either completely transparent or completely solid). I need to find within image A a pixel which (with its' neighbors) most closely resembles image B, OR the pixel that...

Optimizing Haskell code

I'm trying to learn Haskell and after an article in reddit about Markov text chains, I decided to implement Markov text generation first in Python and now in Haskell. However I noticed that my python implementation is way faster than the Haskell version, even Haskell is compiled to native code. I am wondering what I should do to make the...

Java app: Load all resources at startup time

Java loads the resources as they are needed. This make my tiny small desktop application to be very slow when opening a window. How can I do to load all the resources when starting the app? Is something related to classloaders? EDIT: does this code work if the files are inside a jar? EDIT2: Note that the aim is not to reduce the start...

Too Many Left Outer Joins in Entity Framework 4?

I have a product entity, which has 0 or 1 "BestSeller" entities. For some reason when I say: db.Products.OrderBy(p => p.BestSeller.rating).ToList(); the SQL I get has an "extra" outer join (below). And if I add on a second 0 or 1 relation ship, and order by both, then I get 4 outer joins. It seems like each such entity is producing ...

Optimizing Levenshtein distance algorithm

I have a stored procedure that uses Levenshtein distance to determine the result closest to what the user typed. The only thing really affecting the speed is the function that calculates the Levenshtein distance for all the records before selecting the record with the lowest distance (I've verified this by putting a 0 in place of the cal...

Fast find object by string property

Hello, colleagues. I've got task to fast find object by its string property. Object: class DicDomain { public virtual string Id{ get; set; } public virtual string Name { get; set; } } For storing my object I use List[T] dictionary where T is DicDomain for now . I've got 5-10 such lists, which contain about 500-20000 at e...

Help optimizing a query with 16 subqueries

I have indexes/primaries on all appropriate ID fields for each type. I'm wondering though how I could make this more efficient. It takes a while to load the page with only 15,000 rows and that'll quickly grow to 500k. The $whereSql variable simply has a few more parameters for the main ebay_archive_listing table. NOTE: This is all do...

Fastest way to compare Objects of type DateTime

I made this. Is this the fastest way to find lastest DateTime of my collection of DateTimes? I'm wondering if there is a method for what i'm doing inside the foreach, but even if there is, I can't see how it can be faster than what i all ready got. List<StateLog> stateLogs = db.StateLog.Where(p => p.ProductID == product.ProductID).ToLi...

How to optimize this javascript code?

I have a jsp which uses a lot of javascript and it's just not fast enough. I would like to optimize it so first, here's a part of the code: In the jsp I have the initialization: window.onload = function () { formCollection.pageSize.value = "<%= pagingSize%>"; elemCollection = iDom3.Table.all["spis"].XML.DOM; <% ...

iPhone - dequeueReusableCellWithIdentifier usage

Hi, I'm working on a iPhone app which has a pretty large UITableView with data taken from the web, so I'm trying to optimize its creation and usage. I found out that dequeueReusableCellWithIdentifier is pretty useful, but after seeing many source codes using this, I'm wondering if the usage I make of this function is the good one. Her...

Fastest way to find the rotation of a vector

I have two 2D vectors, say u and v, defined by cartesian coordinates. Imagine that vectors are needles of a clock. I'm looking for the fastest way to find out, using python, if v is after or before u (or in other words find out in wich half plane is v, regarding to position of u). For the purpose of the problem if vectors are aligned an...

MySQL query paralyzes site

Once in a while, at random intervals, our website gets completely paralyzed. Looking at SHOW FULL PROCESSLIST;, I've noticed that when this happens, there is a specific query that is "Copying to tmp table" for a loooong time (sometimes 350 seconds), and almost all the other queries are "Locked". The part I don't understand is that 90% ...

Ways to optimize Android App code based on function call stack?

I've been told that Android OS stores all function calls in a stack. This can lead to many problems and cause the 'hiccups' during runtime, even if a program is functionalized properly, correct? So the question is, how can we prevent this from happening? The obvious solution is to functionalize less, along with other sensible acts such ...

Effective optimization strategies on modern C++ compilers

I'm working on scientific code that is very performance-critical. An initial version of the code has been written and tested, and now, with profiler in hand, it's time to start shaving cycles from the hot spots. It's well-known that some optimizations, e.g. loop unrolling, are handled these days much more effectively by the compiler tha...

Ternary Operators in JavaScript Without an "Else"

I've been using them forever, and I love them. To me they see cleaner and i can scan faster, but ever since I've been using them i've always had to put null in the else conditions that don't have anything. Is there anyway around it? E.g. condition ? x=true : null ; basically, is there a way to do: condition ? x=true; Now it shows up as...

SEO Google - Navigation Title vs. Page Heading

Hi, i was wondering if anyone knows if theres a connection between what a navigation item is named and the page heading it goes to - does this have an impact on SEO? so for example, if i had in my navigation menu an item called About Us, but when you click it you come to a page with the heading Learn Who We Are (i.e. wrapped in [h1] he...

reduce image size in bytes without resize and quality lose in c#

Hi I m using C#.NET 4.0 I have an jpeg image and i want to reduce its size in bytes .I don't want to change the image size in manner of height and width and not want to lose image quality.Some bit of reduce quality is not an issue. I try to make it a thumbnail image but it reduce the size according to height and width. I can't found a...

Webcrawler, feedback?

Hey folks, every once in a while I have the need to automate data collection tasks from websites. Sometimes I need a bunch of URLs from a directory, sometimes I need an XML sitemap (yes, I know there is lots of software for that and online services). Anyways, as follow up to my previous question I've written a little webcrawler that can...

Single Large v/s Multiple Small MySQL tables for storing Options

Hi there, I'm aware of several question on this forum relating to this. But I'm not talking about splitting tables for the same entity (like user for example) Suppose I have a huge options table that stores list options like Gender, Marital Status, and many more domain specific groups with same structure. I plan to capture in a OPTIONS ...

Help with optimizing C# function via C and/or Assembly

I have this C# method which I'm trying to optimize: // assume arrays are same dimensions private void DoSomething(int[] bigArray1, int[] bigArray2) { int data1; byte A1, B1, C1, D1; int data2; byte A2, B2, C2, D2; for (int i = 0; i < bigArray1.Length; i++) { data1 = bigArray1[i]; data2 = bigArray2...