Example: spectral_performance
Figure 10.5 — Example: Spectral Performance
Crate: cfd-suite (workspace root)
Run: cargo run --example spectral_performance
Source: examples/spectral_performance.rs
What This Example Demonstrates
Apollo-backed FFT round-trip and spectral-derivative accuracy on a 32-point
sin + 0.5·cos signal, verifying that cfd-3d’s spectral wrapper correctly
delegates plan reuse to apollo-fft.
| API | Purpose |
|---|---|
FourierTransform::<f64>::new(n) | Build reusable FFT plan |
transform.forward(&signal) | Forward DFT |
transform.inverse(&spectrum) | Inverse DFT |
SpectralDerivative::<f64>::new(n) | Spectral derivative operator |
derivative.derivative(&signal, 1) | First derivative in spectral space |
Key Code Snippet
use cfd_3d::spectral::{FourierTransform, SpectralDerivative};
use leto::Array1;
let n = 32;
let transform = FourierTransform::<f64>::new(n)?;
let signal = Array1::from_shape_fn([n], |[i]| {
let x = 2.0 * PI * i as f64 / n as f64;
x.sin() + 0.5 * (2.0 * x).cos()
});
let spectrum = transform.forward(&signal)?;
let recovered = transform.inverse(&spectrum)?;
let err = signal.iter().zip(recovered.iter())
.map(|(a, b)| (a - b).abs()).fold(0.0_f64, f64::max);
assert!(err < 1e-12, "round-trip error = {err:.3e}");Atlas Integration
apollo-fft owns the reusable FFTW-style plans. cfd-3d’s FourierTransform
is a thin wrapper that routes into apollo-fft plan objects so CFDrs never
allocates planning buffers itself. This is the zero-copy, SSOT design for
spectral methods across the Atlas stack.