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Questions tagged [bignum]

Common computer-jargon term to refer to arbitrary-precision math and data-types. The term "arbitrary-precision" refers to the ability of a machine to perform numerical computations whose precision is limited only by the available memory.

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openssl hex2bn and bn2hex will not original string, but always a long postfix

Playing with openssl BN_hex2bn and BN_bn2hex. Expecting to get the original string after hex2bn and then bn2hex, but always got a longer string, with the first past the same as the original string, but a long post fix. Followin gis the…
user1470393
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Kattis Bignum division by powers of 10

I'm trying to implement bignum division by powers of 10. Specifically, this is a kattis problem: https://open.kattis.com/problems/divideby100 I believe my answer is correct but I get a time limit exceeded warning. I know it's due to the insert…
user2953932
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Why a bignumber is shown incomplete in ECLiPSe Prolog?

I use the latest version of ECLiPSe Prolog 64-bit for Windows, then I compile the code: :- op(200, yf, !). !(N, F) :- fac(N, 1, F). fac(0, F0, F) :- !, F=F0. fac(N, F0, F) :- N1 is N-1, F1 is F0*N, fac(N1, F1, F). Query entered: ?- X is 100000 !. X…
T. S. Larsen
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OpenSSL BN_exp() Usage

I have a small program that uses BIGNUM functions BN_exp() and BN_mod_exp() on 64-byte big integers (that are generated via BN_generate_prime_ex()). Every time I compile and run, the program pauses forever while computing the first call to BN_exp().…
jmu_nova
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Change the decimal places of an existing number in bignumber.js?

If I've got a BigNumber (http://mikemcl.github.io/bignumber.js/) with a particular DECIMAL_PLACES: let BN = BigNumber.another({ DECIMAL_PLACES: 0 }) a = new BN(10) How can I change the number of decimal places used for a particular operation? For…
David Wolever
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Send fixed array vs dynamic array over socket

I am trying to send a BIGNUM (from openssl/bn.h) over socket, but its behaviour is strange. I use BN_bn2bin() to convert BIGNUM to array of unsigned char and send it over socket using send(). But what the client receives is corrupted. Why? Here's a…
xtt
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Using big numbers in C with GMP

i'm havin trouble with a code that is returning a nunber that is bigger than that C can handle. I installed the GMP library but with all the tutorials that i found on the internet i can't seem to make it work. Here is the code with the GMP library's…
Hamilton D
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How can I Implement the library GMP.mpz to generate big numbers in Pike?

When I enter the command: pow(9,999999); I obtain the following: Bad argument 1 to pow(). Exponent too large. Unknown program: pow(Gmp.mpz(999999)) -:1: 9->pow(@0=Gmp.mpz(999999)) HilfeInput:1: HilfeInput()->___HilfeWrapper() Somebody would be…
WerthJK
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Big numbers in C

I'm implementing RSA in C. I'm using "unsigned long long int" (Top limit: 18446744073709551615). The problems come when I have to calculate thing like 4294967296 ^ 2. It should be 18446744073709551616, but I get 0 (overflow). I mean, I need to…
Alan
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rust, bignums and windows

I've got rust 1.18.0 on windows 10 and I'd like to write something that uses bignums. The rug library looks like a good choice, but a cargo build on a project using it fails because building gmp calls ln -s somewhere down the line. Is there a rust…
user1569030
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script with big numbers take days

i am trying to run this script and its already run for 2 days. and still dont get answer. i tried long instead int. what am i supposed to do? what is the better way to work with big numbers like this? …
DR.P
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pow() function gives wrong result

I want to execute this math function: 3^(3^1000000000) mod 1000000007 the result of this is: 930782551 But do it directly in python takes a huge amount of time, and the program hangs: return pow(3,pow(3,1000000000),1000000007) So I thought that…
Don't call me
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Function to RoundUP as Microsoft Excel does, in Javascript

Days ago, I started a project in which i needed to do some measure calculation; specifically: statistic calculation. Well, thats not the problem, the problem came with rounding floating numbers (numbers with decimals), and the way javascript deals…
crsuarezf
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Bignum library, slow prime generator

I am developing a bignum library: http://pastebin.com/nFgF3zjW I implemented the Miller-Rabin algorithm (isprime()), but it is extremely slow, compared to for example OpenSSL's BN_is_prime_fasttest. I tried profiling and the functions that are…
Ledio Berdellima
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How to convert an IBAN to an Integer?

Note, this is not about using libraries or any specific programming language. I just want to understand the following concept, from Wikipedia, Validating the IBAN: Example (fictitious United Kingdom bank, sort code 12-34-56, account number…
q9f
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