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bors[bot] a49013e338 Merge #59 
59: Added `MulAdd` and `MulAddAssign` traits r=cuviper a=regexident

Both `f32` and `f64` implement fused multiply-add, which computes `(self * a) + b` with only one rounding error. This produces a more accurate result with better performance than a separate multiplication operation followed by an add:

```rust
fn mul_add(self, a: f32, b: f32) -> f32[src]
```

It is however not possible to make use of this in a generic context by abstracting over a trait.

My concrete use-case is machine learning, [gradient descent](https://en.wikipedia.org/wiki/Gradient_descent) to be specific,  
where the core operation of updating the gradient could make use of `mul_add` for both its `weights: Vector` as well as its `bias: f32`:

```rust
struct Perceptron {
  weights: Vector,
  bias: f32,
}

impl MulAdd<f32, Self> for Vector {
  // ...
}

impl Perceptron {
  fn learn(&mut self, example: Vector, expected: f32, learning_rate: f32) {
    let alpha = self.error(example, expected, learning_rate);
    self.weights = example.mul_add(alpha, self.weights);
    self.bias = self.bias.mul_add(alpha, self.bias)
  }
}
```

(The actual impl of `Vector` would be generic over its value type: `Vector<T>`, thus requiring the trait.)

Co-authored-by: Vincent Esche <regexident@gmail.com>
Co-authored-by: Josh Stone <cuviper@gmail.com>
 		2018-05-04 19:12:41 +00:00
ci CI typo fix 2018-02-01 11:56:13 -08:00
src Merge #59 2018-05-04 19:12:41 +00:00
.gitignore Update num-macros to Rust master 2015-05-14 10:19:47 -07:00
.travis.yml Move num-traits to its own repo 2017-12-18 17:35:41 -08:00
Cargo.toml Release 0.2.2 2018-03-18 16:27:31 -07:00
LICENSE-APACHE Initial seeding from rust repo 2014-09-16 10:35:35 -07:00
LICENSE-MIT Initial seeding from rust repo 2014-09-16 10:35:35 -07:00
README.md Merge #32 2018-02-07 22:26:47 +00:00
RELEASES.md Release 0.2.2 2018-03-18 16:27:31 -07:00
bors.toml Enable bors-ng 2017-07-08 22:29:48 -07:00

README.md

num-traits

crate documentation minimum rustc 1.8 Travis status

Numeric traits for generic mathematics in Rust.

Usage

Add this to your Cargo.toml:

[dependencies]
num-traits = "0.2"

and this to your crate root:

extern crate num_traits;

Features

This crate can be used without the standard library (#![no_std]) by disabling the default std feature. Use this in Cargo.toml:

[dependencies.num-traits]
version = "0.2"
default-features = false

The Float and Real traits are only available when std is enabled. The FloatCore trait is always available.

Releases

Release notes are available in RELEASES.md.

Compatibility

The num-traits crate is tested for rustc 1.8 and greater.