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  • How to create a magic square in PHP?

    - by TerranRich
    I'd like to try my hand at creating a Magic Square in PHP (i.e. a grid of numbers that all add up to the same value), but I really don't know where to start. I know of the many methods that create magic square, such as starting "1" at a fixed position, then moving in a specific direction with each iteration. But that doesn't create a truly randomized Magic Square, which is what I'm aiming for. I want to be able to generate an N-by-N Magic Square of N² numbers where each row and column adds up to N(N²+1)/2 (e.g. a 5x5 square where all rows/columns add up to 65 — the diagonals don't matter). Can anybody provide a starting point? I don't want anybody to do the work for me, I just need to know how to start such a project? I know of one generator, written in Java (http://www.dr-mikes-math-games-for-kids.com/how-to-make-a-magic-square.html) but the last Java experience I had was over 10 years ago before I quickly abandoned it. Therefore, I don't really understand what the code is actually doing. I did notice, however, that when you generate a new square, it shows the numbers 1-25 (for a 5x5 square), in order, before quickly generating a fresh randomized square.

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  • java number exceeds long.max_value - how to detect?

    - by jurchiks
    I'm having problems detecting if a sum/multiplication of two numbers exceeds the maximum value of a long integer. Example code: long a = 2 * Long.MAX_VALUE; System.out.println("long.max * smth > long.max... or is it? a=" + a); This gives me -2, while I would expect it to throw a NumberFormatException... Is there a simple way of making this work? Because I have some code that does multiplications in nested IF blocks or additions in a loop and I would hate to add more IFs to each IF or inside the loop. Edit: oh well, it seems that this answer from another question is the most appropriate for what I need: http://stackoverflow.com/a/9057367/540394 I don't want to do boxing/unboxing as it adds unnecassary overhead, and this way is very short, which is a huge plus to me. I'll just write two short functions to do these checks and return the min or max long. Edit2: here's the function for limiting a long to its min/max value according to the answer I linked to above: /** * @param a : one of the two numbers added/multiplied * @param b : the other of the two numbers * @param c : the result of the addition/multiplication * @return the minimum or maximum value of a long integer if addition/multiplication of a and b is less than Long.MIN_VALUE or more than Long.MAX_VALUE */ public static long limitLong(long a, long b, long c) { return (((a > 0) && (b > 0) && (c <= 0)) ? Long.MAX_VALUE : (((a < 0) && (b < 0) && (c >= 0)) ? Long.MIN_VALUE : c)); } Tell me if you think this is wrong.

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  • Unexpected crash while using looking phone numbers in iPhone address book

    - by FX
    I have a rather unexpected result with the following code: ABAddressBookRef addressBook = ABAddressBookCreate(); CFArrayRef people = ABAddressBookCopyArrayOfAllPeople(addressBook); CFIndex nPeople = ABAddressBookGetPersonCount(addressBook); NSLog (@"npeople = %d = %d", nPeople, CFArrayGetCount(people)); for (CFIndex i = 0; i < nPeople; i++) { ABRecordRef record = CFArrayGetValueAtIndex(people,i); ABMultiValueRef numbers = ABRecordCopyValue(record, kABPersonPhoneProperty); CFIndex count = ABMultiValueGetCount(numbers); NSLog (@"%d %d", i, count); } I never reach the second NSLog, it crashes on the call to ABMultiValueGetCount with: : * -[NSCFString count]: unrecognized selector sent to instance 0x383e72f4 : Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '** -[NSCFString count]: unrecognized selector sent to instance 0x383e72f4' In short, it's behaving as if my "numbers" variable was an NSString. While I wrote the code above myself, the same can be found in many examples on the web. Does someone here spot anything wrong with it? Oh, and also: it only crashes in Release mode (in debug mode, all is fine).

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  • 3x3 array = 10 numbers

    - by user1708505
    i have this code #include <math.h> #include <stdio.h> const int n = 3; const int s = 3; int getm(int mat[n][s]); int printm(int mat[n][s]); int main() { int m[n][s]; getm(m); printm(m); return 0; } int getm(int mat[n][s]) { for(int x = 0;x < n;x++) { for (int y = 0;y<s;y++) { scanf("%i ", &mat[x][y]); } } return 0; } int printm(int mat[n][s]) { for(int x = 0;x<n;x++) { for(int y = 0;y<s;y++) { printf("%i ", mat[x][y]); if(y==(s-1)) { printf("\n"); } } } } which shoud ask for 9 numbers to make a 3x3 matrix array, but it actually asks for 10 numbers, printm is working well - printing only 9 numbers. Where is error?

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  • iptables, blocking large numbers of IP Addresses

    - by Twirrim
    I'm looking to block IP addresses in a relatively automated fashion if they look to be 'screen scraping' content from websites that we host. In the past this was achieved by some ingenious perl scripts and OpenBSD's pf. pf is great in that you can provide it nice tables of IP addresses and it will efficiently handle blocking based on them. However for various reasons (before my time) they made the decision to switch to CentOS. iptables doesn't natively provide the ability to block large numbers of addresses (I'm told it wasn't unusual to be blocking 5000+), and I'm a bit cautious over adding that many rules into an iptable. ipt_recent would be awesome for doing this, plus it provides a lot of flexibility for just severely slowing down access, but there is a bug in the CentOS kernel that is stopping me from using it (reported, but awaiting fix). Using ipset would entail compiling a more up-to-date version of iptables than comes with CentOS which whilst I'm perfectly capable of doing it, I'd rather not do from a patching, security and consistency perspective. Other than those two it looks like nfblock is a reasonable alternative. Is anyone aware of other ways of achieving this? Are my concerns about several thousand IP addresses in iptables as individual rules unfounded?

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  • TCP Handshake and port numbers

    - by Guido
    (I have a question about the TCP handshake and how port numbers are assigned, if this does not belong here, let me know.) Hi, I'm studying TCP/IP from the book "Internetworking with TCP/IP" by Douglas Comer. In the TCP chapter it mentions that TCP defines an "endpoint" as a pair (IP address, port number), and a connection is defined by two endpoints. This has a few implications, such as, a local TCP port could be in several connections at once, as long as there are no two from the same IP and the same remote port. This also means that the amount of established connections is almost limitless (2^16 for every IPv4 address. 2^48 in total). Now, in class, I was told that when one connects to a listening port, both sides agree on a different port to use, so the communication can happen and the listener socket remains free. This was also my belief before reading the book. Now I feel like I should obviously trust the book (It's Comer!), but is there any truth to the other explanation? Thanks

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  • iptables, blocking large numbers of IP Addresses

    - by Twirrim
    I'm looking to block IP addresses in a relatively automated fashion if they look to be 'screen scraping' content from websites that we host. In the past this was achieved by some ingenious perl scripts and OpenBSD's pf. pf is great in that you can provide it nice tables of IP addresses and it will efficiently handle blocking based on them. However for various reasons (before my time) they made the decision to switch to CentOS. iptables doesn't natively provide the ability to block large numbers of addresses (I'm told it wasn't unusual to be blocking 5000+), and I'm a bit cautious over adding that many rules into an iptable. ipt_recent would be awesome for doing this, plus it provides a lot of flexibility for just severely slowing down access, but there is a bug in the CentOS kernel that is stopping me from using it (reported, but awaiting fix). Using ipset would entail compiling a more up-to-date version of iptables than comes with CentOS which whilst I'm perfectly capable of doing it, I'd rather not do from a patching, security and consistency perspective. Other than those two it looks like nfblock is a reasonable alternative. Is anyone aware of other ways of achieving this? Are my concerns about several thousand IP addresses in iptables as individual rules unfounded?

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  • Python- Convert a mixed number to a float

    - by user345660
    I want to make a function that converts mixed numbers and fractions (as strings) to floats. Here's some examples: '1 1/2' -> 1.5 '11/2' -> 5.5 '7/8' -> 0.875 '3' -> 3 '7.7' -> 7.7 I'm currently using this function, but I think it could be improved. It also doesn't handle numbers that are already in decimal representation def mixedtofloat(txt): mixednum = re.compile("(\\d+) (\\d+)\\/(\\d+)",re.IGNORECASE|re.DOTALL) fraction = re.compile("(\\d+)\\/(\\d+)",re.IGNORECASE|re.DOTALL) integer = re.compile("(\\d+)",re.IGNORECASE|re.DOTALL) m = mixednum.search(txt) n = fraction.search(txt) o = integer.search(txt) if m: return float(m.group(1))+(float(m.group(2))/float(m.group(3))) elif n: return float(n.group(1))/float(n.group(2)) elif o: return float(o.group(1)) else: return txt Thanks!

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  • C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

    - by m3ntat
    My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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  • Hashing words to numbers with respect to definition

    - by thornate
    As part of a larger project, I need to read in text and represent each word as a number. For example, if the program reads in "Every good boy deserves fruit", then I would get a table that converts 'every' to '1742', 'good' to '977513', etc. Now, obviously I can just use a hashing algorithm to get these numbers. However, it would be more useful if words with similar meanings had numerical values close to each other, so that 'good' becomes '6827' and 'great' becomes '6835', etc. As another option, instead of a simple integer representing each number, it would be even better to have a vector made up of multiple numbers, eg (lexical_category, tense, classification, specific_word) where lexical_category is noun/verb/adjective/etc, tense is future/past/present, classification defines a wide set of general topics and specific_word is much the same as described in the previous paragraph. Does any such an algorithm exist? If not, can you give me any tips on how to get started on developing one myself? I code in C++.

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  • Display page numbers in a excel sheet generated using C#.NET

    - by constant learner
    Hello Stackers Does anyone have an idea on how to include or input the page numbers in the excel sheet generated using C# code. I use the libraries available in Microsoft.Office.Interop.Excel to generate the file. However by default in the output i cannot see the page numbers. I know to enable this via excel options (View -- Header and Footer ...) but i want to automate this via C#. Is this possible, if yes kindly share the snippet for the same. Thanks Constant Learner

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  • Getting Line Numbers for Errors Thrown in SQL Server CLR Runtime

    - by fetucine53
    Hi all, I've created a CLR stored procedure that I'm running on SQL 2k5 and I'm wondering if there's any way to get line numbers for exceptions thrown by the .NET code. When an Exception is thrown, I get something along the lines of Msg 6522, Level 16, State 1, Procedure myProcedure, Line 0 A .NET Framework error occurred during execution of user-defined routine or aggregate "myProcedure": System.Exception: testing exception System.Exception: at DummyDLL.myProcedure (String dummyInput) . Is there some way I can load the assembly to give me specific line numbers rather than just the function in which the error was thrown? The assembly itself was compiled with a .pdb, but SQL 2k5 doesn't appear to be reading it in when I load the assembly initially. Thanks!

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  • Dealing with unwanted port numbers on localhost when debugging in Visual Studio

    - by Dan Bailiff
    So when I'm trying to debug a project in Visual Studio, I'll often have 1 or more services that I need to call. These services are separate projects and I'll launch them in separate instances of VS. ASP dev server kindly launches them with temporary port numbers attached. This would be fine except for my programs are looking for an IP without a port attached. (Typically it's as simple as "localhost"!) I've coped by using web config settings and changing the xml to use the port number while debugging. This still doesn't always work and occasionally I'll still have to fudge it and insert port numbers as strings in code! UGH! Then I have to remember to undo all the port herding code before deployment... I want to stop doing this: string _strBaseURL = String.Format("http://{0}:2277", ConfigurationManager.AppSettings["myservice_ip"].ToString()); What is the best practice here? Am I doomed to port herding while debugging VS apps?

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  • Reading ASCII numbers using "D" instead of "E" for scientific notation using C

    - by Arrieta
    Hello, I have a list of numbers which looks like this: 1.234D+1 or 1.234D-02. I want to read the file using C. The function atof will merely ignore the D and translate only the mantissa. The function fscanf will not accept the format '%10.6e' because it expects an E instead of a D in the exponent. When I ran into this problem in Python, I have up and merely used a string substitution before converting from string to float. But in C, I am sure there must be another way. So, how would you read a file with numbers using D instead of E for scientific notation? Notice that I do not mean how to read the strings themselves, but rather how to convert them to floats. Thanks.

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  • Sequence numbers best practice

    - by Abdullah Jibaly
    What's the best practice or well known methods to implement sequence numbers for business entities such as invoices, purchase orders, job numbers, etc? I want to be able to save the latest value in the database and be able to set it programatically. Is it OK to use a table for this purpose that has a SEQUENCE_NAME, SEQUENCE_NUMBER tuple? I know some databases have a first class sequence type but others (eg, MySQL) do not so it's not something I want to rely on. If a table is used to hold these sequences what is the right way to get and increment them in a synchronized fashion to ensure no data inconsistencies arise?

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  • Algorithm to generate a list of unique combinations based on a list of numbers

    - by ross
    I would like to efficiently generate a unique list of combinations of numbers based on a starting list of numbers. example start list = [1,2,3,4,5] but the algorithm should work for [1,2,3...n] result = [1],[2],[3],[4],[5] [1,2],[1,3],[1,4],[1,5] [1,2,3],[1,2,4],[1,2,5] [1,3,4],[1,3,5],[1,4,5] [2,3],[2,4],[2,5] [2,3,4],[2,3,5] [3,4],[3,5] [3,4,5] [4,5] Note. I don't want duplicate combinations, although I could live with them, eg in the above example I don't really need the combination [1,3,2] because it already present as [1,2,3]

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  • java reading numbers, interpreting as octal, want interpreted as string

    - by user331401
    hello, i am having an issue, where java is reading an array list from a YAML file of numbers, or strings, and it is interpreting the numbers as octal if it has a leading 0, and no 8-9 digit. is there a way to force java to read the yaml field as a string? code: ArrayList recordrarray = (ArrayList) sect.get("recordnum"); if (recordrarray != null) { recno = join (recordrarray, " "); } HAVE ALSO TRIED: Iterator<String> iter = recordrarray.iterator(); if (iter.hasNext()) recno = " " +String.valueOf(iter.next()); System.out.println(" this recnum:" + recno); while (iter.hasNext()){ recno += ""+String.valueOf(iter.next())); System.out.println(" done recnum:" + String.valueOf(iter.next())); } the input is such: 061456 changes to 25390 061506 changes to 25414 061559 - FINE it took a while to figure out what it was doing, and apparently this is a common issue for java, ideas? thanks

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  • Sum of Fibonacci numbers

    - by Rafal
    Hi, I'm rather new to Haskell. The problem is to find the sum of all even Fibonacci numbers not greater than 4 million. I can't use lists. If I understand correctly, the below solution is wrong, because it uses lists: my_sum = sum $ filter (even) $ takeWhile (< 4000000) fibs Where fibs is the list of all Fibonacci numbers. Somehow, I find it difficult not to think in Haskell in terms of lists. Could anyone guide me to a solution to this problem? Regards

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  • Regular Expression for finding phone numbers

    - by Rocky
    Hello Everyone, I am new to Stackoverflow and I have a quick question. Let's assume we are given a large number of HTML files (large as in theoretically infinite). How can I use Regular Expressions to extract the list of Phone Numbers from all those files? Explanation/expression will be really appreciated. The Phone numbers can be any of the following formats: (123) 456 7899 (123).456.7899 (123)-456-7899 123-456-7899 123 456 7899 1234567899 Thanks a lot for all your help and have a good one!

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  • Best Way to Generate Unique and consecutives numbers in Oracle

    - by RRUZ
    I need to generate unique and consecutive numbers (for use on an invoice), in a fast and reliable way. currently use a Oracle sequence, but in some cases generated numbers are not consecutive because of exceptions that may occur. I thought a couple of solutions to manage this problem, but neither of they convincing me. What solution do you recommend? Use a select max () SELECT MAX (NVL (doc_num, 0)) +1 FROM invoices Use a table to store the last number generated for the invoice. UPDATE docs_numbers SET last_invoice = last_invoice + 1 Another Solution?

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