Fast, Vectorizable method of taking floating point number modulus of special primes?

Posted by caffiend on Stack Overflow See other posts from Stack Overflow or by caffiend
Published on 2010-03-16T19:58:13Z Indexed on 2010/03/16 20:01 UTC
Read the original article Hit count: 232

Filed under:

floating-point

|

simd

|

math

|

algorithm

|

language-agnostic

Is there a fast method for taking the modulus of a floating point number?

With integers, there are tricks for Mersenne primes, so that its possible to calculate y = x MOD 2^31 without needing division.

Can any similar tricks be applied for floating point numbers?
Preferably, in a way that can be converted into vector/SIMD operations, or moved into GPGPU code.

The primes I'm interested in would be 2^7 and 2^31, although if there are more efficient ones for floating point numbers, those would be welcome.

© Stack Overflow or respective owner

Related posts about floating-point

Comparing floating point values

as seen on Stack Overflow - Search for 'Stack Overflow'
I just read a statement about the floating point value comparison Floating point values shall not be compared using either the == or != operators. Most floating point values have no exact binary representation and have a limited precision. If so what is the best method for comparing two floating… >>> More
understanding floating point variables

as seen on Stack Overflow - Search for 'Stack Overflow'
There is some problem, i can't understand anyway. look at this code please <script type="text/javascript"> function math(x) { var y; y = x*10; alert(y); } </script> <input type="button" onclick="math(0.011)"> What must be alerted after i click on button? i think 0.11… >>> More
floating point hex octal binary

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am working on a calculator that allows you to perform calculations past the decimal point in octal, hexadecimal, binary, and of course decimal. I am having trouble though finding a way to convert floating point decimal numbers to floating point hexadecimal, octal, binary and vice versa. The… >>> More
What is a Bias Value of Floating Point Numbers?

as seen on Stack Overflow - Search for 'Stack Overflow'
In learning how floating point numbers are represented in computers I have come across the term "bias value" that I do not quite understand. The bias value in floating point numbers has to do with the negative and positiveness of the exponent part of a floating point number. The bias value of a… >>> More
Why are floating point values so prolific?

as seen on Stack Overflow - Search for 'Stack Overflow'
So, title says it all. Why are floating point values so prolific in computer programming. Due to problems like rounding errors, and not being able to even accurately represent numbers such as 0.1, I really can't see how they got as far as they did. I understand that the computation is faster… >>> More

Related posts about simd

Common SIMD techniques

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi! Where can I find information about common SIMD tricks? I have an instruction set and know, how to write non-tricky SIMD code, but I know, SIMD now is much more powerful. It can hold complex conditional branchless code. For example (ARMv6), the following sequence of instructions sets each byte… >>> More
What approach to take for SIMD optimizations

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am trying to optimize below code for SIMD operations (8way/4way/2way SIMD whiechever possible and if it gives gains in performance) I am tryin to analyze it first on paper to understand the algorithm used. How can i optimize it for SIMD:- void idct(uint8_t *dst, int stride, int16_t *input… >>> More
Benefit of using multiple SIMD instruction sets simultaneously

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm writing a highly parallel application that's multithreaded. I've already got an SSE accelerated thread class written. If I were to write an MMX accelerated thread class, then run both at the same time (one SSE thread and one MMX thread per core) would the performance improve noticeably? I would… >>> More
SSE SIMD Optimization For Loop

as seen on Stack Overflow - Search for 'Stack Overflow'
I have some code in a loop for(int i = 0; i < n; i++) { u[i] = c * u[i] + s * b[i]; } So, u and b are vectors of the same length, and c and s are scalars. Is this code a good candidate for vectorization for use with SSE in order to get a speedup? >>> More
implement SIMD in C++

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm working on a bit of code and I'm trying to optimize it as much as possible, basically get it running under a certain time limit. The following makes the call... static affinity_partitioner ap; parallel_for(blocked_range<size_t>(0, T), LoopBody(score), ap); ... and the following is what… >>> More