I have a list of items I want to buy. The items are offered by different shops and different prices. The shops have individual delivery costs. I'm looking for an optimal shopping strategy (and a java library supporting it) to purchase all of the items with a minimal total price. Example: Item1 is offered at Shop1 for $100, at Shop2 fo...
These languages do not support mutually recursive functions optimization 'natively', so I guess it must be trampoline or.. heh.. rewriting as a loop) Do I miss something? UPDATE: It seems that I did lie about FSharp, but I just didn't see an example of mutual tail-calls while googling ...
Ok, so here's my problem. My iPhone app is 1.2MB on disk. Granted I have a bunch of Images for the GUI buttons and backgrounds, etc. In-memory, my app takes up a whopping 15MB! That means if I then take a picture with the camera, 8MB default, it gives a memory warning (several) even before the picker calls its delegate! How can I te...
Having read up recently on yahoo's web optimisation tips and using YSlow I've implemented a few of their ideas on one of my sites http://www.gwynfryncottages.com you can see the file here http://www.gwynfryncottages.com/js/gw-custom.js. While this technique seems to work perfectly on most occasions, and really does speed up the site, b...
Hi, I'm new to R, and I'm having trouble figuring out how to replace the FOR loop in the function below. The function estimates a population mean. Any help at all would be much appreciated. Thank you! myFunc<- function(){ myFRAME <- read.csv(file="2008short.csv",head=TRUE,sep=",") meanTotal <- 0 for(i in 1:100) { mySample <- sampl...
Hi guys, I just wanted to know what happens behind my program when I declare and initialize a variable and later initialize it again with other values, e.g. an ArrayList or something similar. What happens in my RAM, when I say e.g. this: ArrayList<String> al = new ArrayList<String>(); ...add values, work with it and so on.... al = new...
Hi all, I'm trying to make a little iPad tool's for drawing simple geometrical objects (rect, rounded rect, ellipse, star, ...). My goal is to make something very close to Keynote (drawing feature), i.e. let the user add a rect (for instance), resizing it and moving it. I want too the user can select many objects and move them together....
Hello. I'm trying to calculate the dot-product of two very sparse associative arrays. The arrays contain an ID and a value, so the calculation should be done only on those IDs that are common to both arrays, e.g. <(1, 0.5), (3, 0.7), (12, 1.3)> * <(2, 0.4), (3, 2.3), (12, 4.7)> = 0.7*2.3 + 1.3*4.7 . My implementation (call it dict) cur...
Hi, I'm newbie in t-sql, and I wonder why this query executes so long ? Is there any way to optimize this ?? update aggregateflags set value=@value where objecttype=@objecttype and objectcode=@objectcode and storagetype=@storagetype and value != 2 and type=@type IF @@ROWCOUNT=0 Select * from aggregateflags where objecttype=@objectty...
I have a lot of if-elif-else statements in my code if message == '0' or message == '3' or message == '5' or message == '7': ... elif message == '1' or message == '2' or message == '4' or message == '6' or message == '8': ... else: ... Is it possible to format this in a more space-saving way? I tried it this way: if messag...
I have a DataTable with column Value and column Name that has 30000 rows. Now i would like to get very fast Name from row that Value has specified. How to do this fast? I have like 40000 requests with various Values to this table. I'm interested in solution in C# and not on the database side. ...
Hello, I'm designing a city building game and got into a problem. Imagine Sierra's Caesar III game mechanics: you have many city districts with one market each. There are several granaries over the distance connected with a directed weighted graph. The difference: people (here cars) are units that form traffic jams (here goes the graph...
Hi All: I have following TSQL, 3 IDs (@EmpID, @DeptID and @CityID) are passed in and it could all have NULL or any one could be NULL. See following scenario: -- Very Narrow (all IDs are passed in) IF(@EmpID IS NOT NULL AND @DeptID IS NOT NULL AND @CityID IS NOT NULL) BEGIN SELECT e.EmpName ,d.DeptName ...
The idea is somewhat similar to what Apple has done in the OpenGL stack. I want to have that a bit more general. Basically, I want to have specialised and optimised variants of some code for some specific cases. In other words: I have given an algorithm/code for a function (let B = {0,1}) f : B^n -> B^m Now, I special a specific cas...
I have a 20 gig table that has a large amount of inserts and updates daily. This table is also frequently searched. I'd like to know if the MySQL indices can become fragmented and perhaps need to be rebuilt or something similar. I'm finding it difficult to figure out which of the CHECK TABLE, REPAIR TABLE or something similar? Any gui...
Hi, I am writing a C++ number crunching application, where the bottleneck is a function that has to calculate for double: template<class T> inline T sqr(const T& x){return x*x;} and another one that calculates Base dist2(const Point& p) const { return sqr(x-p.x) + sqr(y-p.y) + sqr(z-p.z); } These operations take 80% of t...
Today I was looking for website optimization content and I found an article talking about move JavaScript scripts to the bottom of the HTML page. Is this valid with W3C's recommendations? I learned that all JavaScript must be inside of head tag... Thank you. ...
I'm writing a parser in PHP which must be able to handle large in-memory strings, so this is a somewhat important issue. (ie, please don't "premature optimize" flame me, please) How does the substr function work? Does it make a second copy of the string data in memory, or does it reference the original? Should I worry about calling, for...
I'm retrieving a list of nhibernate entites which have relationships to other tables/entities. I've noticed instead of NHibernate performing JOINS and populating the properties, it retrieves the entity and then calls a select for each property. For example if a user can have many roles and I retrieve a user from the DB, Nhibernate retrie...
I was wondering if adding a LIMIT 1 to a query would speed up the processing? For example... I have a query that will most of the time return 1 result, but will occasionaly return 10's, 100's or even 1000's of records. But I will only ever want the first record. Would the limit 1 speed things up or make no difference? I know I could ...