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We use cargo vendor to generate a .cargo/config file and the vendor directory. Vendoring allows us to lock our dependencies and to modify them easily from the top level Cargo.toml. We vendor all dependencies, including the crates.io ones, which allows for network isolated builds. Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
52 lines
1.6 KiB
Rust
52 lines
1.6 KiB
Rust
// Copyright 2018 Developers of the Rand project.
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// Copyright 2013-2018 The Rust Project Developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! # Monte Carlo estimation of π
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//!
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//! Imagine that we have a square with sides of length 2 and a unit circle
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//! (radius = 1), both centered at the origin. The areas are:
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//!
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//! ```text
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//! area of circle = πr² = π * r * r = π
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//! area of square = 2² = 4
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//! ```
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//!
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//! The circle is entirely within the square, so if we sample many points
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//! randomly from the square, roughly π / 4 of them should be inside the circle.
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//!
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//! We can use the above fact to estimate the value of π: pick many points in
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//! the square at random, calculate the fraction that fall within the circle,
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//! and multiply this fraction by 4.
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#![cfg(feature="std")]
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extern crate rand;
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use rand::distributions::{Distribution, Uniform};
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fn main() {
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let range = Uniform::new(-1.0f64, 1.0);
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let mut rng = rand::thread_rng();
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let total = 1_000_000;
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let mut in_circle = 0;
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for _ in 0..total {
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let a = range.sample(&mut rng);
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let b = range.sample(&mut rng);
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if a*a + b*b <= 1.0 {
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in_circle += 1;
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}
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}
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// prints something close to 3.14159...
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println!("π is approximately {}", 4. * (in_circle as f64) / (total as f64));
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}
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