softposit-rs

Rust port of [SoftPosit] repository.

Such types are supported now:

• P32E2 or P32: 32-bit posit with exponent size ES=2;
• P16E1 or P16: 16-bit posit with ES=1;
• P8E0 or P8: 8-bit posit without exponent bits.

Initial suppot of generic types PxE1{N} and PxE2{N}. Requires nightly rustc and nightly feature to be enabled.

Examples

Convert from f64, Add

``` use softposit::P32;

fn main() { let a = P32::from(12.3); let b = P32::from(154.); let c = a + b; println!("c = {0} or c = {0:?}", c); } ```

Quire

Each Posit type has correspondent Quire type (Q32, Q16, Q8). These types support AddAssign and SubAssign operations. For example:

``` use softposit::{P32, Q32};

// c == 12.30.4 - 6.38.4 == -48; fn main() { let mut q = Q32::init(); q += (P32::from(12.3), P32::from(0.4)); q -= (P32::from(6.3), P32::from(8.4)); let c = q.to_posit(); println!("c = {0} or c = {0:?}", c); } ```

Math

Math functions, like trigonomentic, are partially implemented for P32E2 type. For complex computations use num::Complex type.

Linear algebra

You can also use matrix operations, defined in nalgebra crate by using linalg feature:

``` use softposit::P32;

use nalgebra::{Dynamic, Matrix, VecStorage}; type DMatrix = Matrix>;

fn main() { let a = DMatrix::newrandom(5, 5); println!("Matrix A = {}", a); let decomp = &a.clone().lu(); if let Some(c) = decomp.tryinverse() { println!("Inverse matrix Aˉ¹ = {}", c); println!("Check Identity"); let ones = a * c; println!("A × Aˉ¹ = {}", ones); } else { println!("Matrix A can't be inverted"); } } ```

cargo build --features="linalg,rand"

Benchmarking

cargo bench

| Type | Operation | i3-2310M @ 2.10GHz | i5-3470 @ 3.20GHz | | ----- |:---------:|:------------------:|:-----------------:| | P32E2 | + | 47 MPOPS | 82 MPOPS | | | - | 45 MPOPS | 83 MPOPS | | | * | 56 MPOPS | 99 MPOPS | | | / | 25 MPOPS | 42 MPOPS | | | √⎺⎺ | 48 MPOPS | 92 MPOPS | | | round | 89 MPOPS | 159 MPOPS |