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  • Encode complex number as RGB pixel and back

    - by Vi
    How is it better to encode a complex number into RGB pixel and vice versa? Probably (logarithm of) an absolute value goes to brightness and an argument goes to hue. Desaturated pixes should receive randomized argument in reverse transformation. Something like: 0 - (0,0,0) 1 - (255,0,0) -1 - (0,255,255) 0.5 - (128,0,0) i - (255,255,0) -i - (255,0,255) (0,0,0) - 0 (255,255,255) - e^(i * random) (128,128,128) - 0.5 * e^(i *random) (0,128,128) - -0.5 Are there ready-made formulas for that? Edit: Looks like I just need to convert RGB to HSB and back. Edit 2: Existing RGB - HSV converter fragment: if (hsv.sat == 0) { hsv.hue = 0; // ! return hsv; } I don't want 0. I want random. And not just if hsv.sat==0, but if it is lower that it should be ("should be" means maximum saturation, saturation that is after transformation from complex number).

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  • How are integers converted to strings under the hood?

    - by CrazyJugglerDrummer
    I suppose the real question is how to convert base2/binary to base10. The most common application of this would probably be in creating strings for output: turning a chunk of binary numerical data into an array of characters. How exactly is this done? my guess: Seeing as there probably isn't a string predefined for each numerical value, I'm guessing that the computer goes through each bit of the integer from right to left, each time incrementing the appropriate values in the char array/base10 notation places. If we take the number 160 in binary (10100000), it would know that a 1 in the 8th place means 128, so it places 1 into the third column, 2 in the second, and 8 in the third. The 1 in the 6th column means 32, and it would add those values to the second and first place, carrying over if needed. After this it's an easy conversion to actual char codes.

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  • Computationally simple Pseudo-Gaussian Distribution with varying mean and standard deviation?

    - by mstksg
    This picture from wikipedia has a nice example of the sort of functions I'd ideally like to generate http://en.wikipedia.org/wiki/File:Normal_Distribution_PDF.svg Right now I'm using the Irwin-Hall Distribution, which is more or less a Polynomial approximation of the Gaussian distribution...basically, you use uniform random number generator and iterate it x times, and take the average. The more iterations, the more like a Gaussian Distribution it is. It's pretty nice; however I'd like to be able to have one where I can vary the mean. For example, let's say I wanted a number between the range 0 and 10, but around 7. Like, the mean (if I repeated this function multiple times) would turn out to be 7, but the actual range is 0-10. Is there one I should look up, or should I work on doing some fancy maths with standard Gaussian Distributions?

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  • Best Practices / Patterns for Enterprise Protection/Remediation of SSNs (Social Security Numbers)

    - by Erik Neu
    I am interested in hearing about enterprise solutions for SSN handling. (I looked pretty hard for any pre-existing post on SO, including reviewing the terriffic SO automated "Related Questions" list, and did not find anything, so hopefully this is not a repeat.) First, I think it is important to enumerate the reasons systems/databases use SSNs: (note—these are reasons for de facto current state—I understand that many of them are not good reasons) Required for Interaction with External Entities. This is the most valid case—where external entities your system interfaces with require an SSN. This would typically be government, tax and financial. SSN is used to ensure system-wide uniqueness. SSN has become the default foreign key used internally within the enterprise, to perform cross-system joins. SSN is used for user authentication (e.g., log-on) The enterprise solution that seems optimum to me is to create a single SSN repository that is accessed by all applications needing to look up SSN info. This repository substitutes a globally unique, random 9-digit number (ASN) for the true SSN. I see many benefits to this approach. First of all, it is obviously highly backwards-compatible—all your systems "just" have to go through a major, synchronized, one-time data-cleansing exercise, where they replace the real SSN with the alternate ASN. Also, it is centralized, so it minimizes the scope for inspection and compliance. (Obviously, as a negative, it also creates a single point of failure.) This approach would solve issues 2 and 3, without ever requiring lookups to get the real SSN. For issue #1, authorized systems could provide an ASN, and be returned the real SSN. This would of course be done over secure connections, and the requesting systems would never persist the full SSN. Also, if the requesting system only needs the last 4 digits of the SSN, then that is all that would ever be passed. Issue #4 could be handled the same way as issue #1, though obviously the best thing would be to move away from having users supply an SSN for log-on. There are a couple of papers on this: UC Berkely: http://bit.ly/bdZPjQ Oracle Vault: bit.ly/cikbi1

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  • RANDOM Number Generation in C

    - by CVS-2600Hertz-wordpress-com
    Recently i have begun development of a simple game. It is improved version of an earlier version that i had developed. Large part of the game's success depends on Random number generation in different modes: MODE1 - Truly Random mode myRand(min,max,mode=1); Should return me a random integer b/w min & max. MODE2 - Pseudo Random : Token out of a bag mode myRand(min,max,mode=2); Should return me a random integer b/w min & max. Also should internally keep track of the values returned and must not return the same value again until all the other values are returned atleast once. MODE3 - Pseudo Random : Human mode myRand(min,max,mode=3); Should return me a random integer b/w min & max. The randomisation ought to be not purely mathematically random, rather random as user perceive it. How Humans see RANDOM. * Assume the code is time-critical (i.e. any performance optimisations are welcome) * Pseudo-code will do but an implementation in C is what i'm looking for. * Please keep it simple. A single function should be sufficient (thats what i'm looking for) Thank You

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  • how to make a name from random numbers?

    - by blood
    my program makes a random name that could have a-z this code makes a 16 char name but :( my code wont make the name and idk why :( can anyone show me what's wrong with this? char name[16]; void make_random_name() { byte loop = -1; for(;;) { loop++; srand((unsigned)time(0)); int random_integer; random_integer = (rand()%10)+1; switch(random_integer) { case '1': name[loop] = 'A'; break; case '2': name[loop] = 'B'; break; case '3': name[loop] = 'C'; break; case '4': name[loop] = 'D'; break; case '5': name[loop] = 'E'; break; case '6': name[loop] = 'F'; break; case '7': name[loop] = 'G'; break; case '8': name[loop] = 'Z'; break; case '9': name[loop] = 'H'; break; } cout << name << "\n"; if(loop > 15) { break; } } }

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  • Storing high precision latitude/longitude numbers in iOS Core Data

    - by Bryan
    I'm trying to store Latitude/Longitudes in core data. These end up being anywhere from 6-20 digit precision. And for whatever reason, i had them as floats in Core Data, its rounding them and not giving me the exact values back. I tried "decimal" type, with no luck either. Are NSStrings my only other option? EDIT NSManagedObject: @interface Event : NSManagedObject { } @property (nonatomic, retain) NSDecimalNumber * dec; @property (nonatomic, retain) NSDate * timeStamp; @property (nonatomic, retain) NSNumber * flo; @property (nonatomic, retain) NSNumber * doub; Here's the code for a sample number that I store into core data: NSNumber *n = [NSDecimalNumber decimalNumberWithString:@"-97.12345678901234567890123456789"]; Code to access it again: NSNumber *n = [managedObject valueForKey:@"dec"]; NSNumber *f = [managedObject valueForKey:@"flo"]; NSNumber *d = [managedObject valueForKey:@"doub"]; Printed values: Printing description of n: -97.1234567890124 Printing description of f: <CFNumber 0x603f250 [0xfef3e0]>{value = -97.12345678901235146441, type = kCFNumberFloat64Type} Printing description of d: <CFNumber 0x6040310 [0xfef3e0]>{value = -97.12345678901235146441, type = kCFNumberFloat64Type}

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  • Is this a correct porting of java.util.Random in objectiveC

    - by dipu
    I have ported the code inside java.util.Random class in objectivec. I want to have an identical random number generator so that it synchs with the server app running on java. Now is this a safe porting and if not is there a way to mimic AtomicLong as it is found in java? Please see my code below. static long long multiplier = 0x5DEECE66DL; static long addend = 0xBL; static long long mask = (0x1000000000000001L << 48) - 1; -(void) initWithSeed:(long long) seed1 { [self setRandomSeed: 0L];// = new AtomicLong(0L); [self setSeed: seed1]; } -(int) next:(int)bits { long long oldseed, nextseed; long long seed1 = [self.randomSeed longLongValue]; //AtomicLong //do { oldseed = seed1; nextseed = (oldseed * multiplier + addend) & mask; //} while (!seed.compareAndSet(oldseed, nextseed)); [self setRandomSeed: [NSNumber numberWithLongLong:nextseed]]; ///int ret = (int)(nextseed >>> (48 - bits)); int ret = (unsigned int)(nextseed >> (48 - bits)); return ret; } -(void) setSeed:(long long) seed1 { seed1 = (seed1 ^ multiplier) & mask; [self setRandomSeed: [NSNumber numberWithLongLong:seed1]]; }

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  • Count the prime numbers from 2 to 100 with simpler code than this

    - by RufioLJ
    It has to be with just functions, variables, loops, etc (Basic stuff). I'm having trouble coming up with the code from scratch from what I've I learned so far(Should be able to do it). Makes me really mad :/. If you could give me step by step to make sure I understand I'd really really appreciated. Thanks a bunch in advanced. How could I get the same result with a simpler code than this one: var primes=4; for (var counter = 2; counter <= 100; counter = counter + 1) { var isPrime = 0; if(isPrime === 0){ if(counter === 2){console.log(counter);} else if(counter === 3){console.log(counter);} else if(counter === 5){console.log(counter);} else if(counter === 7){console.log(counter);} else if(counter % 2 === 0){isPrime=0;} else if(counter % 3 === 0){isPrime=0;} else if(counter % 5 === 0){isPrime=0;} else if(counter % 7 === 0){isPrime=0;} else { console.log(counter); primes = primes + 1; } } } console.log("Counted: "+primes+" primes");

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  • Multiplication of 2 positive numbers giving a negative result

    - by krandiash
    My program is an implementation of a bloom filter. However, when I'm storing my hash function results in the bit array, the function (of the form f(i) = (a*i + b) % m where a,b,i,m are all positive integers) is giving me a negative result. The problem seems to be in the calculation of a*i which is coming out to be negative. Ignore the print statements in the code; those were for debugging. Basically, the value of temp in this block of code is coming out to be negative and so I'm getting an ArrayOutOfBoundsException. m is the bit array length, z is the number of hash functions being used, S is the set of values which are members of this bloom filter and H stores the values of a and b for the hash functions f1, f2, ..., fz. public static int[] makeBitArray(int m, int z, ArrayList<Integer> S, int[] H) { int[] C = new int[m]; for (int i = 0; i < z; i++) { for (int q = 0; q < S.size() ; q++) { System.out.println(H[2*i]); int temp = S.get(q)*(H[2*i]); System.out.println(temp); System.out.println(S.get(q)); System.out.println(H[2*i + 1]); System.out.println(m); int t = ((H[2*i]*S.get(q)) + H[2*i + 1])%m; System.out.println(t); C[t] = 1; } } return C; } Any help is appreciated.

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  • How to generate random numbers of lognormal distribution within specific range in Matlab

    - by Harpreet
    My grain sizes are defined as D=[1.19,1.00,0.84,0.71,0.59,0.50,0.42]. The problem is described below in steps. Grain sizes should follow lognormal distribution. The mean of the grain sizes is fixed as 0.84 and the standard deviation should be as low as possible but not zero. 90% of the grains (by weight %) fall in the size range of 1.19 to 0.59, and the rest 10% fall in size range of 0.50 to 0.42. Now I want to find the probabilities (weight percentage) of the grains falling in each grain size. It is allowable to split this grain size distribution into further small sizes but it must always be in the range of 1.19 and 0.42, i.e. 'D' can be continuous but 0.42 < D < 1.19. I need it fast. I tried on my own but I am not able to get the correct result. I am getting negative probabilities (weight percentages). Thanks to anyone who helps. I didn't incorporate the point 3 as I came to know about that condition later. Here are simple steps I tried: %% D=[1.19,1.00,0.84,0.71,0.59,0.50,0.42]; s=0.30; % std dev of the lognormal distribution m=0.84; % mean of the lognormal distribution mu=log(m^2/sqrt(s^2+m^2)); % mean of the associated normal dist. sigma=sqrt(log((s^2/m^2)+1)); % std dev of the associated normal dist. [r,c]=size(D); for i=1:c D(i)=mu+(sigma.*randn(1)); w(i)=(log(D(i))-mu)/sigma; % the probability or the wt. percentage of the grain sizes end grain_size=exp(D); %%

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  • showing surrounding page numbers

    - by Tony Vipros
    I've been doing some pagination recently and used the following: if ( $totalPages > $pagesToShow ) { $start = $pageNumber - floor($pagesToShow/2); $end = $pageNumber + floor($pagesToShow/2); while ( $start < 1 ) { $start++; $end++; } while ( $end > $totalPages ) { $start--; $end--; } } else { $start = 1; $end = $totalPages; } to work out where to start and end the list of surrounding pages. So that a paging list can be created like << < 1 2 3 4 5 '. Just wondering if there is a better method as using loops like that seems a little odd.

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  • Sorting Numbers ins a Object.

    - by user133611
    Hi I have an NSMutableArray of objects, let's say 'Person' Objects. I want to sort the NSMutable Array by person.savings i.e if suppose person having savings 1000,1050,500,1200,2000,1050 i want the Array in the ascending order. Thank You.

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  • How to generate a random number, then display it on screen?

    - by Dan
    Ok, im fairly new to android but i have managed to teach myself the basics, i am making an app where you press a button , and a new screen opens and it shows a randomly generated number, the only problem is i dont know how to generate and display the random number, i have been searching the web for ages and have only found little snippets of information , that dosent really make sense to me. :/ If someone could help me , or even give me just a little bit of info that should guide me in the right direction it would be great

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  • how to determine base of a number?

    - by evil.coder
    Given a integer number and its reresentation in some arbitrary number system. The purpose is to find the base of the number system. For example, number is 10 and representation is 000010, then the base should be 10. Another example: number 21 representation is 0010101 then base is 2. One more example is: number is 6 and representation os 10100 then base is sqrt(2). Does anyone have any idea how to solve such problem?

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  • integrating uppercut and cc.net

    - by deepasun
    I am trying to integrate uppercut and cc.net for getting build and revision... What do I have to put in the codebuild folder? while running cc.net, I'm getting svn folder Unable to execute file [D:\CodeBuild\abc\svn]. The file may not exist or may not be executable. ---> System.ComponentModel.Win32Exception: The system cannot find the file specified Without cc.net integration can we get both build and revision incremented? When will build and revision get incremented?

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  • Is -1 a magic number? An anti-pattern? A code smell? Quotes and guidelines from authorities

    - by polygenelubricants
    I've seen -1 used in various APIs, most commonly when searching into a "collection" with zero-based indices, usually to indicate the "not found" index. This "works" because -1 is never a legal index to begin with. It seems that any negative number should work, but I think -1 is almost always used, as some sort of (unwritten?) convention. I would like to limit the scope to Java at least for now. My questions are: What are the official words from Sun regarding using -1 as a "special" return value like this? What quotes are there regarding this issue, from e.g. James Gosling, Josh Bloch, or even other authoritative figures outside of Java? What were some of the notable discussions regarding this issue in the past?

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  • Convert NSFileSystemSize to Gigabytes

    - by AWright4911
    I need to convert NSFileSystemSize to Gigabytes. NSDictionary * fsAttributes = [ [NSFileManager defaultManager] fileSystemAttributesAtPath:NSTemporaryDirectory()]; NSNumber *totalSize = [fsAttributes objectForKey:NSFileSystemSize]; NSString *sizeInGB = [NSString stringWithFormat:@"\n\n %3.2f GB",[totalSize floatValue] / 107374824]; //returns 69.86 GB any ideas why it doesnt return at leat 8.0GB's?

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  • Precision of cos(atan2(y,x)) versus using complex <double>, C++

    - by Ivan
    Hi all, I'm writing some coordinate transformations (more specifically the Joukoswky Transform, Wikipedia Joukowsky Transform), and I'm interested in performance, but of course precision. I'm trying to do the coordinate transformations in two ways: 1) Calculating the real and complex parts in separate, using double precision, as below: double r2 = chi.x*chi.x + chi.y*chi.y; //double sq = pow(r2,-0.5*n) + pow(r2,0.5*n); //slow!!! double sq = sqrt(r2); //way faster! double co = cos(atan2(chi.y,chi.x)); double si = sin(atan2(chi.y,chi.x)); Z.x = 0.5*(co*sq + co/sq); Z.y = 0.5*si*sq; where chi and Z are simple structures with double x and y as members. 2) Using complex : Z = 0.5 * (chi + (1.0 / chi)); Where Z and chi are complex . There interesting part is that indeed the case 1) is faster (about 20%), but the precision is bad, giving error in the third decimal number after the comma after the inverse transform, while the complex gives back the exact number. So, the problem is on the cos(atan2), sin(atan2)? But if it is, how the complex handles that? Thanks!

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  • VB6: Question about version numbers of dependent OCXs

    - by Craig Johnston
    Is it important for a VB6 app to refer to certain OCX versions? I have noticed that if I put my VB6 app code through the IDE on one machine then the form files will refer to different version of some OCXs than if I use another machine. What is the rule of thumb with this? Is it safe to assume that most of these old OCX versions will be compatible with each other and so I shouldn't worry? Some of the OCXs in question are: RICHTX32.OCX v1.1 and v1.2 COMCTL32.OCX v1.2 and v1.3

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