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<section id='main' class="content mod">
<h1 class='fqn'><span class='in-band'>Crate <a class='mod' href=''>num</a></span><span class='out-of-band'><span id='render-detail'>
<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
[<span class='inner'>−</span>]
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</span><a id='src-0' class='srclink' href='../src/num/lib.rs.html#11-213' title='goto source code'>[src]</a></span></h1>
<div class='docblock'><p>A collection of numeric types and traits for Rust.</p>
<p>This includes new types for big integers, rationals, and complex numbers,
new traits for generic programming on numeric properties like <code>Integer</code>,
and generic range iterators.</p>
<h2 id='example' class='section-header'><a href='#example'>Example</a></h2>
<p>This example uses the BigRational type and <a href="https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method">Newton's method</a> to
approximate a square root to arbitrary precision:</p>
<span class='rusttest'>extern crate num;
#[cfg(all(feature = "bigint", feature="rational"))]
mod test {
use num::FromPrimitive;
use num::bigint::BigInt;
use num::rational::{Ratio, BigRational};
pub
fn approx_sqrt(number: u64, iterations: usize) -> BigRational {
let start: Ratio<BigInt> = Ratio::from_integer(FromPrimitive::from_u64(number).unwrap());
let mut approx = start.clone();
for _ in 0..iterations {
approx = (&approx + (&start / &approx)) /
Ratio::from_integer(FromPrimitive::from_u64(2).unwrap());
}
approx
}
}
#[cfg(not(all(feature = "bigint", feature="rational")))]
mod test { pub fn approx_sqrt(n: u64, _: usize) -> u64 { n } }
use test::approx_sqrt;
fn main() {
println!("{}", approx_sqrt(10, 4)); // prints 4057691201/1283082416
}
</span><pre class='rust rust-example-rendered'>
<span class='kw'>extern</span> <span class='kw'>crate</span> <span class='ident'>num</span>;
<span class='kw'>use</span> <span class='ident'>num</span>::<span class='ident'>FromPrimitive</span>;
<span class='kw'>use</span> <span class='ident'>num</span>::<span class='ident'>bigint</span>::<span class='ident'>BigInt</span>;
<span class='kw'>use</span> <span class='ident'>num</span>::<span class='ident'>rational</span>::{<span class='ident'>Ratio</span>, <span class='ident'>BigRational</span>};
<span class='kw'>fn</span> <span class='ident'>approx_sqrt</span>(<span class='ident'>number</span>: <span class='ident'>u64</span>, <span class='ident'>iterations</span>: <span class='ident'>usize</span>) <span class='op'>-></span> <span class='ident'>BigRational</span> {
<span class='kw'>let</span> <span class='ident'>start</span>: <span class='ident'>Ratio</span><span class='op'><</span><span class='ident'>BigInt</span><span class='op'>></span> <span class='op'>=</span> <span class='ident'>Ratio</span>::<span class='ident'>from_integer</span>(<span class='ident'>FromPrimitive</span>::<span class='ident'>from_u64</span>(<span class='ident'>number</span>).<span class='ident'>unwrap</span>());
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>approx</span> <span class='op'>=</span> <span class='ident'>start</span>.<span class='ident'>clone</span>();
<span class='kw'>for</span> _ <span class='kw'>in</span> <span class='number'>0</span>..<span class='ident'>iterations</span> {
<span class='ident'>approx</span> <span class='op'>=</span> (<span class='kw-2'>&</span><span class='ident'>approx</span> <span class='op'>+</span> (<span class='kw-2'>&</span><span class='ident'>start</span> <span class='op'>/</span> <span class='kw-2'>&</span><span class='ident'>approx</span>)) <span class='op'>/</span>
<span class='ident'>Ratio</span>::<span class='ident'>from_integer</span>(<span class='ident'>FromPrimitive</span>::<span class='ident'>from_u64</span>(<span class='number'>2</span>).<span class='ident'>unwrap</span>());
}
<span class='ident'>approx</span>
}
<span class='kw'>fn</span> <span class='ident'>main</span>() {
<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"{}"</span>, <span class='ident'>approx_sqrt</span>(<span class='number'>10</span>, <span class='number'>4</span>)); <span class='comment'>// prints 4057691201/1283082416</span>
}
</pre>
</div><h2 id='reexports' class='section-header'><a href="#reexports">Reexports</a></h2>
<table><tr><td><code>pub use bigint::{<a class='struct' href='../num/bigint/struct.BigInt.html' title='num::bigint::BigInt'>BigInt</a>, <a class='struct' href='../num/bigint/struct.BigUint.html' title='num::bigint::BigUint'>BigUint</a>};</code></td></tr><tr><td><code>pub use rational::<a class='type' href='../num/rational/type.Rational.html' title='num::rational::Rational'>Rational</a>;</code></td></tr><tr><td><code>pub use rational::<a class='type' href='../num/rational/type.BigRational.html' title='num::rational::BigRational'>BigRational</a>;</code></td></tr><tr><td><code>pub use complex::<a class='struct' href='../num/complex/struct.Complex.html' title='num::complex::Complex'>Complex</a>;</code></td></tr><tr><td><code>pub use integer::<a class='trait' href='../num/integer/trait.Integer.html' title='num::integer::Integer'>Integer</a>;</code></td></tr><tr><td><code>pub use iter::{<a class='fn' href='../num/iter/fn.range.html' title='num::iter::range'>range</a>, <a class='fn' href='../num/iter/fn.range_inclusive.html' title='num::iter::range_inclusive'>range_inclusive</a>, <a class='fn' href='../num/iter/fn.range_step.html' title='num::iter::range_step'>range_step</a>, <a class='fn' href='../num/iter/fn.range_step_inclusive.html' title='num::iter::range_step_inclusive'>range_step_inclusive</a>};</code></td></tr><tr><td><code>pub use traits::{<a class='trait' href='../num/traits/trait.Num.html' title='num::traits::Num'>Num</a>, <a class='trait' href='../num/traits/trait.Zero.html' title='num::traits::Zero'>Zero</a>, <a class='trait' href='../num/traits/trait.One.html' title='num::traits::One'>One</a>, <a class='trait' href='../num/traits/trait.Signed.html' title='num::traits::Signed'>Signed</a>, <a class='trait' href='../num/traits/trait.Unsigned.html' title='num::traits::Unsigned'>Unsigned</a>, <a class='trait' href='../num/traits/trait.Bounded.html' title='num::traits::Bounded'>Bounded</a>, <a class='trait' href='../num/traits/trait.Saturating.html' title='num::traits::Saturating'>Saturating</a>, <a class='trait' href='../num/traits/trait.CheckedAdd.html' title='num::traits::CheckedAdd'>CheckedAdd</a>, <a class='trait' href='../num/traits/trait.CheckedSub.html' title='num::traits::CheckedSub'>CheckedSub</a>, <a class='trait' href='../num/traits/trait.CheckedMul.html' title='num::traits::CheckedMul'>CheckedMul</a>, <a class='trait' href='../num/traits/trait.CheckedDiv.html' title='num::traits::CheckedDiv'>CheckedDiv</a>, <a class='trait' href='../num/traits/trait.PrimInt.html' title='num::traits::PrimInt'>PrimInt</a>, <a class='trait' href='../num/traits/trait.Float.html' title='num::traits::Float'>Float</a>, <a class='trait' href='../num/traits/trait.ToPrimitive.html' title='num::traits::ToPrimitive'>ToPrimitive</a>, <a class='trait' href='../num/traits/trait.FromPrimitive.html' title='num::traits::FromPrimitive'>FromPrimitive</a>, <a class='trait' href='../num/traits/trait.NumCast.html' title='num::traits::NumCast'>NumCast</a>, <a class='fn' href='../num/traits/fn.cast.html' title='num::traits::cast'>cast</a>};</code></td></tr></table><h2 id='modules' class='section-header'><a href="#modules">Modules</a></h2>
<table>
<tr class=' module-item'>
<td><a class='mod' href='bigint/index.html'
title='num::bigint'>bigint</a></td>
<td class='docblock short'>
<p>A Big integer (signed version: <code>BigInt</code>, unsigned version: <code>BigUint</code>).</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='mod' href='complex/index.html'
title='num::complex'>complex</a></td>
<td class='docblock short'>
<p>Complex numbers.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='mod' href='integer/index.html'
title='num::integer'>integer</a></td>
<td class='docblock short'>
<p>Integer trait and functions.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='mod' href='iter/index.html'
title='num::iter'>iter</a></td>
<td class='docblock short'>
<p>External iterators for generic mathematics</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='mod' href='rational/index.html'
title='num::rational'>rational</a></td>
<td class='docblock short'>
<p>Rational numbers</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='mod' href='traits/index.html'
title='num::traits'>traits</a></td>
<td class='docblock short'>
<p>Numeric traits for generic mathematics</p>
</td>
</tr>
</table><h2 id='functions' class='section-header'><a href="#functions">Functions</a></h2>
<table>
<tr class=' module-item'>
<td><a class='fn' href='fn.abs.html'
title='num::abs'>abs</a></td>
<td class='docblock short'>
<p>Computes the absolute value.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='fn' href='fn.abs_sub.html'
title='num::abs_sub'>abs_sub</a></td>
<td class='docblock short'>
<p>The positive difference of two numbers.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='fn' href='fn.checked_pow.html'
title='num::checked_pow'>checked_pow</a></td>
<td class='docblock short'>
<p>Raises a value to the power of exp, returning <code>None</code> if an overflow occurred.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='fn' href='fn.one.html'
title='num::one'>one</a></td>
<td class='docblock short'>
<p>Returns the multiplicative identity, <code>1</code>.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='fn' href='fn.pow.html'
title='num::pow'>pow</a></td>
<td class='docblock short'>
<p>Raises a value to the power of exp, using exponentiation by squaring.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='fn' href='fn.signum.html'
title='num::signum'>signum</a></td>
<td class='docblock short'>
<p>Returns the sign of the number.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class='fn' href='fn.zero.html'
title='num::zero'>zero</a></td>
<td class='docblock short'>
<p>Returns the additive identity, <code>0</code>.</p>
</td>
</tr>
</table></section>
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