biginteger

What should I use for a BigInt class in .NET?

由 断了今生、忘了曾经 提交于 2019-11-28 04:20:49
问题 Until BCL finally ships System.Numeric.BigInt, what do you guys use for arbitrary precision integers? 回答1: You could try mine on codeplex: BigInteger Or here's another: codeproject 回答2: F# has Microsoft.FSharp.Math.BigInt and Microsoft.FSharp.Math.BigNum . 回答3: Also, the J# library includes a BigInt type. Thankfully, all this will be sorted out when the BCL finally ships a standardized BigInt. UPDATE 2012 System.Numberics.BigInteger is now included in the .NET framework. 回答4: Have a look at

Difference between BigInteger.probablePrime() and other primality algorithms in java

由 Deadly 提交于 2019-11-28 04:05:38
问题 I am implementing an RSA encryption program using Java. Right now I am using BigInteger.probablePrime(1024, rnd) to get prime numbers. Here rnd is a random number generated by Random rnd = new Random() . I need to test various speeds of encryption. My questions are: what algorithm does the BigInteger.probablePrime(1024, rnd) use? what is the difference between the algorithm above and other algorithms: like Rabin-Miller, Fermats, Lucas-Lehmer? Thank you. 回答1: BigInteger 's probable prime

BitShifting with BigIntegers in Java

由 社会主义新天地 提交于 2019-11-28 03:46:34
问题 I am implementing DES Encryption in Java with use of BigIntegers. I am left shifting binary keys with Java BigIntegers by doing the BigInteger.leftShift(int n) method. Key of N (Kn) is dependent on the result of the shift of Kn-1. The problem I am getting is that I am printing out the results after each key is generated and the shifting is not the expected out put. The key is split in 2 Cn and Dn (left and right respectively). I am specifically attempting this: "To do a left shift, move each

Fastest algorithm to find if a BigInteger is a prime number or not? [duplicate]

由 爱⌒轻易说出口 提交于 2019-11-28 03:22:59
问题 This question already has answers here : Fastest primality test (3 answers) Closed 4 years ago . I am writing a method that detects if a BigInteger is prime or not. I have used the following code/algorithm to check if a given number is prime or not. But this is extremely slow and takes long time if a number is lets say 10 digits long. public boolean returnPrime(BigInteger testNumber){ int divisorCounter=1; BigInteger index,i ; for ( index= new BigInteger("2"); index.compareTo(testNumber) !=1;

is there anyway to convert from Double to BigInteger?

由 房东的猫 提交于 2019-11-28 02:50:38
问题 Is there anyway to convert from double value to BigInteger ? double doubleValue = 64654679846513164.2; BigInteger bigInteger = (BigInteger) doubleValue; I try to cast it but it didn't work. 回答1: BigInteger is made for holding arbitrary precision integer numbers, not decimals. You can use the BigDecimal class to hold a double. BigDecimal k = BigDecimal.valueOf(doublevalue); In general, you cannot type cast a Java primitive into another class. The exceptions that I know about are the classes

How to work with big numbers in PHP?

由 旧城冷巷雨未停 提交于 2019-11-28 00:48:23
问题 How to work with big numbers in PHP? such as (6*27^0+17*27^1+11*27^2+18*27^3+25*27^4+4*27^5)^65537 回答1: You can go for BCMath to work with big numbers. 回答2: GMP's actually faster than BCMath for bigintegers if you have it installed. If you have neither BCMath or GMP installed you can use phpseclib's pure-php biginteger implementation. That implementation uses GMP or BCmath if they're available, in that order, and it's own internal implementation otherwise. 回答3: There are many options: The GMP

Generating very large random numbers java

由 浪子不回头ぞ 提交于 2019-11-28 00:27:55
问题 How can we generate very large random number in java? I am talking something like 10000 digits? I know we have to use BigInteger but how can we do this? What is the most efficent way of doing something like this? Please provide a small example. Thank you. 回答1: Well, one way is to go to Random.org and download a one of the binary random files. The files are generated from atmospheric noise, so it's very random. I used it for Zobrist keys in my chess engine. Alternatively you could go

C# A random BigInt generator

由 非 Y 不嫁゛ 提交于 2019-11-27 23:36:41
问题 I'm about to implement the DSA algorithm, but there is a problem: choose "p", a prime number with L bits, where 512 <= L <= 1024 and L is a multiple of 64 How can I implement a random generator of that number? Int64 has "only" 63 bits length. 回答1: You can generate a random number with n bits using this code: var rng = new RNGCryptoServiceProvider(); byte[] bytes = new byte[n / 8]; rng.GetBytes(bytes); BigInteger p = new BigInteger(bytes); The result is, of course, random and not necessarily a

byte[] to unsigned BigInteger?

由 泪湿孤枕 提交于 2019-11-27 23:28:38
Motivation: I would like to convert hashes (MD5/SHA1 etc) into decimal integers for the purpose of making barcodes in Code128C. For simplicity, I prefer all the resulting (large) numbers to be positive. I am able to convert byte[] to BigInteger in C#... Sample from what I have so far: byte[] data; byte[] result; BigInteger biResult; result = shaM.ComputeHash(data); biResult = new BigInteger(result); But (rusty CS here) am I correct that a byte array can always be interpreted in two ways: (A): as a signed number (B): as an unsigned number Is it possible to make an UNSIGNED BigInteger from a

What is the best way to represent arbitrarily big numbers in c?

由 纵饮孤独 提交于 2019-11-27 23:17:58
I'm working on a project that requires me to work with numbers larger than the largest numerical datatype in c. I was thinking of using structs with bit fields to represent this, but it's already smelling bad. Anyone got any tips? (Not looking for a library, more of a thought process to go behind doing something like this.) I suggest to first check out the GNU MP Bignum library. If licensing is a problem you have to roll your own. My first choice for the data-type would be a simple array of unsigned chars along with some extra data to denote how large that array is. Something like this:
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