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  • Java - Using Linear Coordinates to Check Against AI [closed]

    - by Oliver Jones
    I'm working on some artificial intelligence, and I want my AI not to run into given coordinates as these are references of a wall/boundary. To begin with, every time my AI hits a wall, it makes a reference to that position (x,y). When it hits the same wall three times, it uses linear check points to 'imagine' there is a wall going through these coordinates. I want to now prevent my AI from going into that wall again. To detect if my coordinates make a straight line, i use: private boolean collinear(double x1, double y1, double x2, double y2, double x3, double y3) { return (y1 - y2) * (x1 - x3) == (y1 - y3) * (x1 - x2); } This returns true is the given points are linear to one another. So my problems are: How do I determine whether my robot is approaching the wall from its current trajectory? Instead of Java 'imagining' theres a line from 1, to 3. But to 'imagine' a line all the way through these linear coordinantes, until infinity (or close). I have a feeling this is going to require some confusing trigonometry? (REPOST: http://stackoverflow.com/questions/13542592/java-using-linear-coordinates-to-check-against-ai)

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  • Top 10 Linked Blogs of 2010

    - by Bill Graziano
    Each week I send out a SQL Server newsletter and include links to interesting blog posts.  I’ve linked to over 500 blog posts so far in 2010.  Late last year I started storing those links in a database so I could do a little reporting.  I tend to link to posts related to the OLTP engine.  I also try to link to the individual blogger in the group blogs.  Unfortunately that wasn’t possible for the SQLCAT and CSS blogs.  I also have a real weakness for posts related to PASS. These are the top 10 blogs that I linked to during the year ordered by the number of posts I linked to. Paul Randal – Paul writes extensively on the internals of the relational engine.  Lots of great posts around transactions, transaction log, disaster recovery, corruption, indexes and DBCC.  I also linked to many of his SQL Server myths posts. Glenn Berry – Glenn writes very interesting posts on how hardware affects SQL Server.  I especially like his posts on the various CPU platforms.  These aren’t necessarily topics that I’m searching for but I really enjoy reading them. The SQLCAT Team – This Microsoft team focuses on the largest and most interesting SQL Server installations.  The regularly publish white papers and best practices. SQL Server CSS Team – These are the top engineers from the Microsoft Customer Service and Support group.  These are the folks you finally talk to after your case has been escalated about 20 times.  They write about the interesting problems they find. Brent Ozar – The posts I linked to mostly focused on the relational engine: CPU, NUMA, SSD drives, performance monitoring, etc.  But Brent writes about a real variety of topics including blogging, social networking, speaking, the MCM, SQL Azure and anything else that seems to strike his fancy.  His posts are always well written and though provoking. Jeremiah Peschka – A number of Jeremiah’s posts weren’t about SQL Server.  He’s very active in the “NoSQL” area and I linked to a number of those posts.  I think it’s important for people to know what other technologies are out there. Brad McGehee – Brad writes about being a DBA including maintenance plans, DBA checklists, compression and audit. Thomas LaRock – I linked to a variety of posts from PBM to networking to 24 Hours of PASS to TDE.  Just a real variety of topics.  Tom always writes with an interesting style usually mixing in a movie theme and/or bacon. Aaron Bertrand – Many of my links this year were Denali features.  He also had a great series on bad habits to kick. Michael J. Swart – This last one surprised me.  There are some well known SQL Server bloggers below Michael on this list.  I linked to posts on indexes, hierarchies, transactions and I/O performance and a variety of other engine related posts.  All are interesting and well thought out.  Many of his non-SQL posts are also very good.  He seems to have an interest in puzzles and other brain teasers.  Michael, I won’t be surprised again!

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  • Haskell - function (that returns a list) on each element in a list

    - by Ben
    The assignment is to create a multiples function and I essentially want todo the following code: map (\t -> scanl (\x y -> x+y) t (repeat t)) listofnumbers The problem is that the scanl function returns a list of results rather than the one which the map function requires. So is there a function that will allow the return of lists?

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  • Random List of numbers in C

    - by Ant
    I have just started a C programming course and so far have only done the basics like printf, read a little on variables etc on the course book. The teacher has tasked us with writing a program that will take a value entered by the user, this will be the number of students in the class (25 at the moment but can be variable). It will then list the number of students randomly and place them in 3 columns. The purpose is to sort students into groups of 3 randomly, then display on the screen in columns. Now my question is not for the code that defeats the object of me attempting the exercise, but how to structure it. I can see that using an array can be used to display the list, but really after some pointers on how best to approach the problem in blocks, then I can attempt to program each block.

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  • Optimal two variable linear regression SQL statement (censoring outliers)

    - by Dave Jarvis
    Problem Am looking to apply the y = mx + b equation (where m is SLOPE, b is INTERCEPT) to a data set, which is retrieved as shown in the SQL code. The values from the (MySQL) query are: SLOPE = 0.0276653965651912 INTERCEPT = -57.2338357550468 SQL Code SELECT ((sum(t.YEAR) * sum(t.AMOUNT)) - (count(1) * sum(t.YEAR * t.AMOUNT))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as SLOPE, ((sum( t.YEAR ) * sum( t.YEAR * t.AMOUNT )) - (sum( t.AMOUNT ) * sum(power(t.YEAR, 2)))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as INTERCEPT FROM (SELECT D.AMOUNT, Y.YEAR FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D WHERE -- For a specific city ... -- C.ID = 8590 AND -- Find all the stations within a 15 unit radius ... -- SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) <15 AND -- Gather all known years for that station ... -- S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND -- The data before 1900 is shaky; insufficient after 2009. -- Y.YEAR BETWEEN 1900 AND 2009 AND -- Filtered by all known months ... -- M.YEAR_REF_ID = Y.ID AND -- Whittled down by category ... -- M.CATEGORY_ID = '001' AND -- Into the valid daily climate data. -- M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR ORDER BY Y.YEAR ) t Data The data is visualized here (with five outliers highlighted): Questions How do I return the y value against all rows without repeating the same query to collect and collate the data? That is, how do I "reuse" the list of t values? How would you change the query to eliminate outliers (at an 85% confidence interval)? The following results (to calculate the start and end points of the line) appear incorrect. Why are the results off by ~10 degrees (e.g., outliers skewing the data)? (1900 * 0.0276653965651912) + (-57.2338357550468) = -4.66958228 (2009 * 0.0276653965651912) + (-57.2338357550468) = -1.65405406 I would have expected the 1900 result to be around 10 (not -4.67) and the 2009 result to be around 11.50 (not -1.65). Thank you!

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  • Optimal two variable linear regression SQL statement

    - by Dave Jarvis
    Problem Am looking to apply the y = mx + b equation (where m is SLOPE, b is INTERCEPT) to a data set, which is retrieved as shown in the SQL code. The values from the (MySQL) query are: SLOPE = 0.0276653965651912 INTERCEPT = -57.2338357550468 SQL Code SELECT ((sum(t.YEAR) * sum(t.AMOUNT)) - (count(1) * sum(t.YEAR * t.AMOUNT))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as SLOPE, ((sum( t.YEAR ) * sum( t.YEAR * t.AMOUNT )) - (sum( t.AMOUNT ) * sum(power(t.YEAR, 2)))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as INTERCEPT FROM (SELECT D.AMOUNT, Y.YEAR FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D WHERE -- For a specific city ... -- C.ID = 8590 AND -- Find all the stations within a 5 unit radius ... -- SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) <15 AND -- Gather all known years for that station ... -- S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND -- The data before 1900 is shaky; and insufficient after 2009. -- Y.YEAR BETWEEN 1900 AND 2009 AND -- Filtered by all known months ... -- M.YEAR_REF_ID = Y.ID AND -- Whittled down by category ... -- M.CATEGORY_ID = '001' AND -- Into the valid daily climate data. -- M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR ORDER BY Y.YEAR ) t Data The data is visualized here: Questions How do I return the y value against all rows without repeating the same query to collect and collate the data? That is, how do I "reuse" the list of t values? How would you change the query to eliminate outliers (at an 85% confidence interval)? The following results (to calculate the start and end points of the line) appear incorrect. Why are the results off by ~10 degrees (e.g., outliers skewing the data)? (1900 * 0.0276653965651912) + (-57.2338357550468) = -4.66958228 (2009 * 0.0276653965651912) + (-57.2338357550468) = -1.65405406 I would have expected the 1900 result to be around 10 (not -4.67) and the 2009 result to be around 11.50 (not -1.65). Thank you!

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  • trying to append a list, but something breaks

    - by romunov
    I'm trying to create an empty list which will have as many elements as there are num.of.walkers. I then try to append, to each created element, a new sub-list (length of new sub-list corresponds to a value in a. When I fiddle around in R everything goes smooth: list.of.dist[[1]] <- vector("list", a[1]) list.of.dist[[2]] <- vector("list", a[2]) list.of.dist[[3]] <- vector("list", a[3]) list.of.dist[[4]] <- vector("list", a[4]) I then try to write a function. Here is my feeble attempt that results in an error. Can someone chip in what am I doing wrong? countNumberOfWalks <- function(walk.df) { list.of.walkers <- sort(unique(walk.df$label)) num.of.walkers <- length(unique(walk.df$label)) #Pre-allocate objects for further manipulation list.of.dist <- vector("list", num.of.walkers) a <- c() # Count the number of walks per walker. for (i in list.of.walkers) { a[i] <- nrow(walk.df[walk.df$label == i,]) } a <- as.vector(a) # Add a sublist (length = number of walks) for each walker. for (i in i:num.of.walkers) { list.of.dist[[i]] <- vector("list", a[i]) } return(list.of.dist) } > num.of.walks.per.walker <- countNumberOfWalks(walk.df) Error in vector("list", a[i]) : vector size cannot be NA

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  • Linked servers SQLNCLI problem. "No transaction is active"

    - by Felipe Fiali
    Im trying to execute a stored procedure and simply insert its results in a temporary table, and I'm getting the following message: The operation could not be performed because OLE DB provider "SQLNCLI" for linked server "MyServerName" was unable to begin a distributed transaction. OLE DB provider "SQLNCLI" for linked server "MyServerName" returned message "No transaction is active.". My query looks like this: INSERT INTO #TABLE EXEC MyServerName.MyDatabase.dbo.MyStoredProcedure Param1, Param2, Param3 Exact column number, names, the problem is not the result. MSDTC is allowed and started in both computers, Remote procedure calling too. The machines are not in the same domain, but I can execute remote queries from my machine and get the result. I can even execute the stored procedure and see its results, I just can't insert it in another table. Help, please? :)

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  • How to optimize simple linked server select query?

    - by tomaszs
    Hello, I have a table called Table with columns: ID (int, primary key, clustered, unique index) TEXT (varchar 15) on a MSSQL linked server called LS. Linked server is on the same server computer. And: When I call: SELECT ID, TEXT FROM OPENQUERY(LS, 'SELECT ID, TEXT FROM Table') It takes 400 ms. When I call: SELECT ID, TEXT FROM LS.dbo.Table It takes 200 ms And when I call the query directly while being at LS server: SELECT ID, TEXT FROM dbo.Table It takes 100 ms. In many places i've read that OPENQUERY is faster, but in this simple case it does not seem to work. What can I do to make this query faster when I call it from another server, not LS directly?

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  • Linked List Sorting with Strings In C

    - by user308583
    I have a struct, with a Name and a single Node called nextName It's a Singly Linked list, and my task is to create the list, based on alphabetical order of the strings. So iff i enter Joe Zolt and Arthur i should get my list structured as Joe Than Joe Zolt Than Arthur Joe Zolt I'm having trouble implementing the correct Algorithm, which would put the pointers in the right order. This is What I have as of Now. Temp would be the name the user just entered and is trying to put into the list, namebox is just a copy of my root, being the whole list if(temp != NULL) { struct node* namebox = root; while (namebox!=NULL && (strcmp((namebox)->name,temp->name) <= 0)) { namebox = namebox->nextName; printf("here"); } temp->nextName = namebox; namebox = temp; root = namebox; This Works right now, if i enter names like CCC BBB than AAA I Get Back AAA BBB CCC when i print But if i put AAA BBB CCC , When i print i only get CCC, it cuts the previous off.

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  • Using FindAll on a List<List<T>> type

    - by Ken Foster
    Assuming public class MyClass { public int ID {get; set; } public string Name {get; set; } } and List<MyClass> classList = //populate with MyClass instances of various IDs I can do List<MyClass> result = classList.FindAll(class => class.ID == 123); and that will give me a list of just classes with ID = 123. Works great, looks elegant. Now, if I had List<List<MyClass>> listOfClassLists = //populate with Lists of MyClass instances How do I get a filtered list where the lists themselves are filtered. I tried List<List<MyClass>> result = listOfClassLists.FindAll (list => list.FindAll(class => class.ID == 123).Count > 0); it looks elegant, but doesn't work. It only includes Lists of classes where at least one class has an ID of 123, but it includes ALL MyClass instances in that list, not just the ones that match. I ended up having to do List<List<MyClass>> result = Results(listOfClassLists, 123); private List<List<MyClass>> Results(List<List<MyClass>> myListOfLists, int id) { List<List<MyClass>> results = new List<List<MyClass>>(); foreach (List<MyClass> myClassList in myListOfLists) { List<MyClass> subList = myClassList.FindAll(myClass => myClass.ID == id); if (subList.Count > 0) results.Add(subList); } return results; } which gets the job done, but isn't that elegant. Just looking for better ways to do a FindAll on a List of Lists. Ken

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  • Query through linked server is very slow

    - by Sergey Olontsev
    I have 2 SQL 2005 servers SRV1 and SRV2. SRV2 is the linked server on SRV1. I run a storep proc with params on SRV2 and it is completed immediately. But when I run the same proc through the linked server on SRV1, for example EXEC [SRV1].DB_TEST.dbo.p_sample_proc it takes about 8-10 minutes to complete. After restarting SRV2 the problem is gone. But some time later it returns. Does anyone have any ideas what it could be?

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  • Unique elements of list within list in python

    - by user2901061
    We are given a list of animals in different zoos and need to find which zoos have animals that are not in any others. The animals of each zoo are separated by spaces, and each zoo is originally separated by a comma. I am currently enumerating over all of the zoos to split each animal and create lists within lists for different zoos as such: for i, zoo in enumerate(zoos): zoos[i] = zoo.split() However, I then do not know how to tell and count how many of the zoos have unique animals. I figure it is something else with enumerate and possibly sets, but cannot get it down exactly. Any help is greatly appreciated. Thanks

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  • Optimizing list comprehension to find pairs of co-prime numbers

    - by user3685422
    Given A,B print the number of pairs (a,b) such that GCD(a,b)=1 and 1<=a<=A and 1<=b<=B. Here is my answer: return len([(x,y) for x in range(1,A+1) for y in range(1,B+1) if gcd(x,y) == 1]) My answer works fine for small ranges but takes enough time if the range is increased. such as 1 <= A <= 10^5 1 <= B <= 10^5 is there a better way to write this or can this be optimized?

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  • C++ stl collections or linked lists

    - by Lucas
    I'm developing a OpenGL based simulation in C++. I'm optmizing my code now and i see throughout the code the frequently use of std:list and std:vector. What is the more performatic: to continue using C++ stl data structs or a pointer based linked list? The main operation that involve std::list and std::vector is open a iterator and loop through all items in the data structs and apply some processing

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  • Adding nodes to a global linked-list

    - by Zack
    I am attempting to construct my first linked list, and having read a basic introduction, have done the following. Firstly, declare a linked list node as: struct errorNode { uint8 error; struct errorNode* next; }; Secondly, define the first node globally as: struct errorNode errorList = {0, NULL}; This has been done to allow each of the libraries that make up my current project to insert errors into a common list. The function to do this is: void errorListWrite(uint8 error) { struct errorNode* newNode = malloc(sizeof(struct errorNode)); newNode->error = error; newNode->next = &errorList; errorList = *newNode; } Whilst this compiles without error, it does not function as expected. I thnk the problem is with the last two statements of the list write function, but I am unsure. A hint as to what I am doing wrong would be most appreciated.

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  • Building a linked list with LINQ

    - by FreshCode
    What is the fastest way to order an unordered list of elements by predecessor (or parent) element index using LINQ? Each element has a unique ID and the ID of that element's predecessor (or parent) element, from which a linked list can be built to represent an ordered state. Example ID | Predecessor's ID --------|-------------------- 20 | 81 81 | NULL 65 | 12 12 | 20 120 | 65 The sorted order is {81, 20, 12, 65, 120}. An (ordered) linked list can easily be assembled iteratively from these elements, but can it be done in fewer LINQ statements? Edit: I should have specified that IDs are not necessarily sequential. I chose 1 to 5 for simplicity. See updated element indices which are random.

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  • concurrent doubly-linked list (1 writer, n-readers)

    - by Arne
    Hi guys, I am back in the field of programming for my Diploma-thesis now and stumbled over the following issue: I need to implement a thread-safe doubly-linked list for one thread writing the list at any position (delete, insert, mutate node data) and one to many threads traversing and reading the list. I am well aware that mutexes can be used to serialize access to the list, still I presume that a naive lock around any write operation will be less than optimal. I am wondering whether there are better variants. (I am well aware that 'optimal' has not much of a practical meaning as long as no exact measure/profiling are available but this is an academic thesis after all..) I am very gratefull for code-samples as well as references to academic granted these have at least a tiny bit of practical relevance. Thanks at lot

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  • Efficient algorithm to generate all solutions of a linear diophantine equation with ai=1

    - by Ben
    I am trying to generate all the solutions for the following equations for a given H. With H=4 : 1) ALL solutions for x_1 + x_2 + x_3 + x_4 =4 2) ALL solutions for x_1 + x_2 + x_3 = 4 3) ALL solutions for x_1 + x_2 = 4 4) ALL solutions for x_1 =4 For my problem, there are always 4 equations to solve (independently from the others). There are a total of 2^(H-1) solutions. For the previous one, here are the solutions : 1) 1 1 1 1 2) 1 1 2 and 1 2 1 and 2 1 1 3) 1 3 and 3 1 and 2 2 4) 4 Here is an R algorithm which solve the problem. library(gtools) H<-4 solutions<-NULL for(i in seq(H)) { res<-permutations(H-i+1,i,repeats.allowed=T) resum<-apply(res,1,sum) id<-which(resum==H) print(paste("solutions with ",i," variables",sep="")) print(res[id,]) } However, this algorithm makes more calculations than needed. I am sure it is possible to go faster. By that, I mean not generating the permutations for which the sums is H Any idea of a better algorithm for a given H ?

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  • Recommended library for linear programming in .Net?

    - by tbone
    Can anyone recommend a library - free, or commercial but affordable ( There are some listed here: http://en.wikipedia.org/wiki/Linear_programming#Solvers_and_scripting_.28programming.29_languages I am just starting out with LP and hope someone can recommend something. I am trying to basically minimize pricing for cell phone subscription services.

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  • Optimal two variable linear regression calculation

    - by Dave Jarvis
    Problem Am looking to apply the y = mx + b equation (where m is SLOPE, b is INTERCEPT) to a data set, which is retrieved as shown in the SQL code. The values from the (MySQL) query are: SLOPE = 0.0276653965651912 INTERCEPT = -57.2338357550468 SQL Code SELECT ((sum(t.YEAR) * sum(t.AMOUNT)) - (count(1) * sum(t.YEAR * t.AMOUNT))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as SLOPE, ((sum( t.YEAR ) * sum( t.YEAR * t.AMOUNT )) - (sum( t.AMOUNT ) * sum(power(t.YEAR, 2)))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as INTERCEPT, FROM (SELECT D.AMOUNT, Y.YEAR FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D WHERE -- For a specific city ... -- C.ID = 8590 AND -- Find all the stations within a 15 unit radius ... -- SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < 15 AND -- Gather all known years for that station ... -- S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND -- The data before 1900 is shaky; insufficient after 2009. -- Y.YEAR BETWEEN 1900 AND 2009 AND -- Filtered by all known months ... -- M.YEAR_REF_ID = Y.ID AND -- Whittled down by category ... -- M.CATEGORY_ID = '001' AND -- Into the valid daily climate data. -- M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR ORDER BY Y.YEAR ) t Data The data is visualized here: Question The following results (to calculate the start and end points of the line) appear incorrect. Why are the results off by ~10 degrees (e.g., outliers skewing the data)? (1900 * 0.0276653965651912) + (-57.2338357550468) = -4.66958228 (2009 * 0.0276653965651912) + (-57.2338357550468) = -1.65405406 I would have expected the 1900 result to be around 10 (not -4.67) and the 2009 result to be around 11.50 (not -1.65). Related Sites Least absolute deviations Robust regression Thank you!

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  • Sparse linear program solver

    - by Jacob
    This great SO answer points to a good sparse solver, but I've got constraints on x (for Ax = b) such that each element in x is >=0 an <=N. The first thing which comes to mind is an LP solver for large sparse matrices. Any ideas/recommendations?

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