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//! Benchmark sqrt and cbrt
#![feature(test)]
extern crate num_integer;
extern crate num_traits;
extern crate test;
use num_integer::Integer;
use num_traits::checked_pow;
use num_traits::{AsPrimitive, PrimInt, WrappingAdd, WrappingMul};
use test::{black_box, Bencher};
trait BenchInteger: Integer + PrimInt + WrappingAdd + WrappingMul + 'static {}
impl<T> BenchInteger for T where T: Integer + PrimInt + WrappingAdd + WrappingMul + 'static {}
fn bench<T, F>(b: &mut Bencher, v: &[T], f: F, n: u32)
where
T: BenchInteger,
F: Fn(&T) -> T,
{
// Pre-validate the results...
for i in v {
let rt = f(i);
if *i >= T::zero() {
let rt1 = rt + T::one();
assert!(rt.pow(n) <= *i);
if let Some(x) = checked_pow(rt1, n as usize) {
assert!(*i < x);
}
} else {
let rt1 = rt - T::one();
assert!(rt < T::zero());
assert!(*i <= rt.pow(n));
if let Some(x) = checked_pow(rt1, n as usize) {
assert!(x < *i);
}
};
}
// Now just run as fast as we can!
b.iter(|| {
for i in v {
black_box(f(i));
}
});
}
// Simple PRNG so we don't have to worry about rand compatibility
fn lcg<T>(x: T) -> T
where
u32: AsPrimitive<T>,
T: BenchInteger,
{
// LCG parameters from Numerical Recipes
// (but we're applying it to arbitrary sizes)
const LCG_A: u32 = 1664525;
const LCG_C: u32 = 1013904223;
x.wrapping_mul(&LCG_A.as_()).wrapping_add(&LCG_C.as_())
}
fn bench_rand<T, F>(b: &mut Bencher, f: F, n: u32)
where
u32: AsPrimitive<T>,
T: BenchInteger,
F: Fn(&T) -> T,
{
let mut x: T = 3u32.as_();
let v: Vec<T> = (0..1000)
.map(|_| {
x = lcg(x);
x
})
.collect();
bench(b, &v, f, n);
}
fn bench_rand_pos<T, F>(b: &mut Bencher, f: F, n: u32)
where
u32: AsPrimitive<T>,
T: BenchInteger,
F: Fn(&T) -> T,
{
let mut x: T = 3u32.as_();
let v: Vec<T> = (0..1000)
.map(|_| {
x = lcg(x);
while x < T::zero() {
x = lcg(x);
}
x
})
.collect();
bench(b, &v, f, n);
}
fn bench_small<T, F>(b: &mut Bencher, f: F, n: u32)
where
u32: AsPrimitive<T>,
T: BenchInteger,
F: Fn(&T) -> T,
{
let v: Vec<T> = (0..1000).map(|i| i.as_()).collect();
bench(b, &v, f, n);
}
fn bench_small_pos<T, F>(b: &mut Bencher, f: F, n: u32)
where
u32: AsPrimitive<T>,
T: BenchInteger,
F: Fn(&T) -> T,
{
let v: Vec<T> = (0..1000)
.map(|i| i.as_().mod_floor(&T::max_value()))
.collect();
bench(b, &v, f, n);
}
macro_rules! bench_roots {
($($T:ident),*) => {$(
mod $T {
use test::Bencher;
use num_integer::Roots;
#[bench]
fn sqrt_rand(b: &mut Bencher) {
::bench_rand_pos(b, $T::sqrt, 2);
}
#[bench]
fn sqrt_small(b: &mut Bencher) {
::bench_small_pos(b, $T::sqrt, 2);
}
#[bench]
fn cbrt_rand(b: &mut Bencher) {
::bench_rand(b, $T::cbrt, 3);
}
#[bench]
fn cbrt_small(b: &mut Bencher) {
::bench_small(b, $T::cbrt, 3);
}
#[bench]
fn fourth_root_rand(b: &mut Bencher) {
::bench_rand_pos(b, |x: &$T| x.nth_root(4), 4);
}
#[bench]
fn fourth_root_small(b: &mut Bencher) {
::bench_small_pos(b, |x: &$T| x.nth_root(4), 4);
}
#[bench]
fn fifth_root_rand(b: &mut Bencher) {
::bench_rand(b, |x: &$T| x.nth_root(5), 5);
}
#[bench]
fn fifth_root_small(b: &mut Bencher) {
::bench_small(b, |x: &$T| x.nth_root(5), 5);
}
}
)*}
}
bench_roots!(i8, i16, i32, i64, i128);
bench_roots!(u8, u16, u32, u64, u128);