1 // The Computer Language Benchmarks Game
2 // http://benchmarksgame.alioth.debian.org/
4 // contributed by the Rust Project Developers
6 // Copyright (c) 2012-2014 The Rust Project Developers
8 // All rights reserved.
10 // Redistribution and use in source and binary forms, with or without
11 // modification, are permitted provided that the following conditions
14 // - Redistributions of source code must retain the above copyright
15 // notice, this list of conditions and the following disclaimer.
17 // - Redistributions in binary form must reproduce the above copyright
18 // notice, this list of conditions and the following disclaimer in
19 // the documentation and/or other materials provided with the
22 // - Neither the name of "The Computer Language Benchmarks Game" nor
23 // the name of "The Computer Language Shootout Benchmarks" nor the
24 // names of its contributors may be used to endorse or promote
25 // products derived from this software without specific prior
26 // written permission.
28 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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39 // OF THE POSSIBILITY OF SUCH DAMAGE.
41 // no-pretty-expanded FIXME #15189
43 #![allow(non_snake_case)]
44 #![feature(unboxed_closures, iter_arith, core_simd, scoped)]
51 let mut args = env::args();
52 let answer = spectralnorm(if env::var_os("RUST_BENCH").is_some() {
54 } else if args.len() < 2 {
57 args.nth(1).unwrap().parse().unwrap()
59 println!("{:.9}", answer);
62 fn spectralnorm(n: usize) -> f64 {
63 assert!(n % 2 == 0, "only even lengths are accepted");
64 let mut u = vec![1.0; n];
65 let mut v = u.clone();
66 let mut tmp = v.clone();
68 mult_AtAv(&u, &mut v, &mut tmp);
69 mult_AtAv(&v, &mut u, &mut tmp);
71 (dot(&u, &v) / dot(&v, &v)).sqrt()
74 fn mult_AtAv(v: &[f64], out: &mut [f64], tmp: &mut [f64]) {
79 fn mult_Av(v: &[f64], out: &mut [f64]) {
80 parallel(out, |start, out| mult(v, out, start, |i, j| A(i, j)));
83 fn mult_Atv(v: &[f64], out: &mut [f64]) {
84 parallel(out, |start, out| mult(v, out, start, |i, j| A(j, i)));
87 fn mult<F>(v: &[f64], out: &mut [f64], start: usize, a: F)
88 where F: Fn(usize, usize) -> f64 {
89 for (i, slot) in out.iter_mut().enumerate().map(|(i, s)| (i + start, s)) {
90 let mut sum = f64x2(0.0, 0.0);
91 for (j, chunk) in v.chunks(2).enumerate().map(|(j, s)| (2 * j, s)) {
92 let top = f64x2(chunk[0], chunk[1]);
93 let bot = f64x2(a(i, j), a(i, j + 1));
94 sum = sum + top / bot;
96 let f64x2(a, b) = sum;
101 fn A(i: usize, j: usize) -> f64 {
102 ((i + j) * (i + j + 1) / 2 + i + 1) as f64
105 fn dot(v: &[f64], u: &[f64]) -> f64 {
106 v.iter().zip(u).map(|(a, b)| *a * *b).sum()
110 // Executes a closure in parallel over the given mutable slice. The closure `f`
111 // is run in parallel and yielded the starting index within `v` as well as a
113 fn parallel<'a,T, F>(v: &mut [T], ref f: F)
114 where T: Send + Sync + 'a,
115 F: Fn(usize, &mut [T]) + Sync + 'a {
116 // FIXME: pick a more appropriate parallel factor
117 // FIXME: replace with thread::scoped when it exists again
119 let size = v.len() / parallelism + 1;
120 v.chunks_mut(size).enumerate().map(|(i, chunk)| {
122 }).collect::<Vec<_>>();