biginteger

I need to convert a Java BigInteger instance to its value in bytes. From the API, I get this method toByteArray() , that returns a byte[] containing the two's-complement representation of this BigInteger. Since all my numbers are positive 128 bits (16 bytes) integer, I don't need the 2's-complement form that give me 128 bits + sign bit (129 bits)... Is there a way to get the standard (without the 2's-complement form) representation directly from a BigInteger? If not, how can I right shift the whole byte[17] array to lose the sign bit in order to get a byte[16] array? Thomas You don't have to

I work to implement an RSA key algorithm. But I couldn't use a 2048-bit value. How I can use it? I want to use big integer. You can use System.Numerics.BigInteger (add a reference to System.Numerics assembly). As mentioned in the comments this might not be the right approach though. Native support for big integers has been introduced in .NET 4.0. Just add an assembly reference to System.Numerics , add a using System.Numerics; declaration at the top of your code file, and you’re good to go. The type you’re after is BigInteger . Sunil Chandurkar Here's using BigInteger . This method Prints

I am working on a CPU-heavy numerical computation app. Without going into many details, it's a computational math research project that involves computing a certain function f(x) for large integer x. Right now everything is implemented in C++ in x64 mode, using native 64-bit ints. That limits me to x<2^64~1.8*10^19. I want to go further, to do that, I need a library that does 128-bit arithmetic. And it has to be very fast. In particular, integer divisions should be fast. Otherwise I'll be sitting here waiting for the results till Thanksgiving. And I'd rather not reinvent the wheel. I found a

What's the best Ruby/Rails way to allow users to use decimals or commas when entering a number into a form? In other words, I would like the user be able to enter 2,000.99 and not get 2.00 in my database. Is there a best practice for this? -- Update --- Does gsub work with floats or bigintegers? Or does rails automatically cut the number off at the , when entering floats or ints into a form? I tried using self.price.gsub(",", "") but get "undefined method `gsub' for 8:Fixnum" where 8 is whatever number I entered in the form. I had a similar problem trying to use localized content inside forms.

I understand that both java.lang.Long and java.math.BigInteger can hold very large natural numbers. I also know Long's max value, but what is the max value for BigInteger? And aside from capacity, would BigInteger ever perform better when working with generally large integers that still fall in Long's range? Question Is the only consideration: is my value too large for Long? AHungerArtist BigInteger is capable of holding far bigger numbers than Long. BigInteger seems capable of holding (2 ^ 32) ^ Integer.MAX_VALUE, though that depends on the implementation (and, even if truly unbounded in the