Add initial benchmarks

benches/bench_fft.rs

@@ -0,0 +1,22 @@
+use criterion::{criterion_group, criterion_main, Criterion};
+
+use num::complex::{Complex, Complex64};
+extern crate rand;
+
+use rand::Rng;
+
+use fft_rs;
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let values: Vec<f64> = rand::thread_rng()
+        .sample_iter(rand::distributions::Standard)
+        .take(1024)
+        .collect();
+
+    c.bench_function("dft", |b| b.iter(|| fft_rs::dft(&values)));
+
+    c.bench_function("fft", |b| b.iter(|| fft_rs::fft(&values)));
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);