2019-07-06 16:29:50 +02:00
|
|
|
/*
|
|
|
|
https://benchmarksgame-team.pages.debian.net/benchmarksgame/performance/spectralnorm.html
|
|
|
|
Added: Pradeep Verghese
|
2019-12-22 00:22:32 +01:00
|
|
|
Benchmarks:
|
2019-07-06 17:13:34 +02:00
|
|
|
Used v -prod spectral.v
|
|
|
|
Command: time ./spectral 5500
|
|
|
|
Output: 1.274224153
|
2019-07-06 16:29:50 +02:00
|
|
|
|
2019-07-06 17:13:34 +02:00
|
|
|
Time: 11.67s user 0.02s system 99% cpu 11.721 total
|
2019-07-06 16:29:50 +02:00
|
|
|
*/
|
|
|
|
module main
|
2019-12-22 00:22:32 +01:00
|
|
|
|
2019-07-06 16:29:50 +02:00
|
|
|
import math
|
|
|
|
import os
|
|
|
|
|
|
|
|
fn evala(i, j int) int {
|
2019-12-22 00:22:32 +01:00
|
|
|
return ((i + j) * (i + j + 1) / 2 + i + 1)
|
2019-07-06 16:29:50 +02:00
|
|
|
}
|
|
|
|
|
2019-12-03 09:52:38 +01:00
|
|
|
fn times(v mut []f64, u []f64) {
|
2020-02-24 17:55:16 +01:00
|
|
|
for i in 0..v.len {
|
2019-12-22 00:22:32 +01:00
|
|
|
mut a := f64(0)
|
2020-02-24 17:55:16 +01:00
|
|
|
for j in 0..u.len {
|
2019-12-22 00:22:32 +01:00
|
|
|
a += u[j] / f64(evala(i, j))
|
|
|
|
}
|
|
|
|
v[i] = a
|
|
|
|
}
|
2019-07-06 16:29:50 +02:00
|
|
|
}
|
|
|
|
|
2019-12-03 09:52:38 +01:00
|
|
|
fn times_trans(v mut []f64, u []f64) {
|
2020-02-24 17:55:16 +01:00
|
|
|
for i in 0..v.len {
|
2019-12-22 00:22:32 +01:00
|
|
|
mut a := f64(0)
|
2020-02-24 17:55:16 +01:00
|
|
|
for j in 0..u.len {
|
2019-12-22 00:22:32 +01:00
|
|
|
a += u[j] / f64(evala(j, i))
|
|
|
|
}
|
|
|
|
v[i] = a
|
|
|
|
}
|
2019-07-06 16:29:50 +02:00
|
|
|
}
|
|
|
|
|
2019-12-03 09:52:38 +01:00
|
|
|
fn a_times_transp(v mut []f64, u []f64) {
|
2019-12-22 00:22:32 +01:00
|
|
|
mut x := [f64(0)].repeat(u.len)
|
|
|
|
times(mut x, u)
|
|
|
|
times_trans(mut v, x)
|
|
|
|
}
|
2019-07-06 16:29:50 +02:00
|
|
|
|
|
|
|
fn main() {
|
2019-12-22 00:22:32 +01:00
|
|
|
args := os.args
|
|
|
|
mut n := int(0)
|
|
|
|
if args.len == 2 {
|
|
|
|
n = args[1].int()
|
|
|
|
}
|
|
|
|
else {
|
|
|
|
n = 0
|
|
|
|
}
|
|
|
|
mut u := [f64(1.0)].repeat(n)
|
|
|
|
mut v := [f64(1.0)].repeat(n)
|
2020-02-24 17:55:16 +01:00
|
|
|
for i in 0..10 {
|
2019-12-22 00:22:32 +01:00
|
|
|
a_times_transp(mut v, u)
|
|
|
|
a_times_transp(mut u, v)
|
|
|
|
}
|
|
|
|
mut vbv := f64(0)
|
|
|
|
mut vv := f64(0)
|
2020-02-24 17:55:16 +01:00
|
|
|
for i in 0..n {
|
2019-12-22 00:22:32 +01:00
|
|
|
vbv += u[i] * v[i]
|
|
|
|
vv += v[i] * v[i]
|
|
|
|
}
|
|
|
|
ans := math.sqrt(vbv / vv)
|
|
|
|
println('${ans:0.9f}')
|
2019-07-06 16:29:50 +02:00
|
|
|
}
|
2019-12-22 00:22:32 +01:00
|
|
|
|