tenferro-fft 0.2.0

FFT extension runtime and public concrete/traced FFT APIs for tenferro.
Documentation 
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use num_complex::Complex64;
use tenferro_cpu::CpuBackend;
use tenferro_tensor::{Tensor, TensorRead, TensorView, TypedTensorView};

use crate::{FftNorm, TensorFftExt, TensorReadFftExt};

fn assert_complex_close(actual: &[Complex64], expected: &[Complex64]) {
    assert_eq!(actual.len(), expected.len());
    for (actual, expected) in actual.iter().zip(expected) {
        assert!(
            (*actual - *expected).norm() < 1.0e-12,
            "actual {actual:?} expected {expected:?}"
        );
    }
}

fn assert_real_close(actual: &[f64], expected: &[f64]) {
    assert_eq!(actual.len(), expected.len());
    for (actual, expected) in actual.iter().zip(expected) {
        assert!(
            (*actual - *expected).abs() < 1.0e-12,
            "actual {actual:?} expected {expected:?}"
        );
    }
}

#[test]
fn public_tensor_fft_ext_executes_real_and_complex_transforms() {
    let mut backend = CpuBackend::new();
    let real = Tensor::from_vec_col_major(vec![4], vec![1.0_f64, 2.0, 3.0, 4.0]).unwrap();
    let full = real.fft(None, -1, FftNorm::Backward, &mut backend).unwrap();
    let onesided = real
        .rfft(None, -1, FftNorm::Backward, &mut backend)
        .unwrap();

    assert_eq!(full.shape(), &[4]);
    assert_complex_close(
        full.as_slice::<Complex64>().unwrap(),
        &[
            Complex64::new(10.0, 0.0),
            Complex64::new(-2.0, 2.0),
            Complex64::new(-2.0, 0.0),
            Complex64::new(-2.0, -2.0),
        ],
    );
    assert_eq!(onesided.shape(), &[3]);
    assert_complex_close(
        onesided.as_slice::<Complex64>().unwrap(),
        &[
            Complex64::new(10.0, 0.0),
            Complex64::new(-2.0, 2.0),
            Complex64::new(-2.0, 0.0),
        ],
    );

    let recovered = full
        .ifft(None, -1, FftNorm::Backward, &mut backend)
        .unwrap();
    assert_complex_close(
        recovered.as_slice::<Complex64>().unwrap(),
        &[
            Complex64::new(1.0, 0.0),
            Complex64::new(2.0, 0.0),
            Complex64::new(3.0, 0.0),
            Complex64::new(4.0, 0.0),
        ],
    );

    let recovered_real = onesided
        .irfft(Some(4), -1, FftNorm::Backward, &mut backend)
        .unwrap();
    assert_real_close(
        recovered_real.as_slice::<f64>().unwrap(),
        &[1.0, 2.0, 3.0, 4.0],
    );
}

#[test]
fn public_tensor_read_fft_ext_accepts_strided_host_views() {
    let mut backend = CpuBackend::new();
    let data = [1.0_f64, 99.0, 2.0, 99.0, 3.0, 99.0, 4.0];
    let view = TypedTensorView::from_slice([4], [2], 0, &data).unwrap();
    let input = TensorRead::from_view(TensorView::F64(view));

    let full = input
        .fft_read(None, -1, FftNorm::Backward, &mut backend)
        .unwrap();
    let onesided = input
        .rfft_read(None, -1, FftNorm::Backward, &mut backend)
        .unwrap();

    assert_complex_close(
        full.as_slice::<Complex64>().unwrap(),
        &[
            Complex64::new(10.0, 0.0),
            Complex64::new(-2.0, 2.0),
            Complex64::new(-2.0, 0.0),
            Complex64::new(-2.0, -2.0),
        ],
    );
    assert_complex_close(
        onesided.as_slice::<Complex64>().unwrap(),
        &[
            Complex64::new(10.0, 0.0),
            Complex64::new(-2.0, 2.0),
            Complex64::new(-2.0, 0.0),
        ],
    );
}

#[test]
fn public_tensor_fft_ext_reports_invalid_dtype_and_shape_errors() {
    let mut backend = CpuBackend::new();
    let bools = Tensor::from_vec_col_major(vec![2], vec![true, false]).unwrap();
    let spectrum = Tensor::from_vec_col_major(
        vec![3],
        vec![
            Complex64::new(10.0, 0.0),
            Complex64::new(-2.0, 2.0),
            Complex64::new(-2.0, 0.0),
        ],
    )
    .unwrap();

    let dtype_err = bools
        .fft(None, -1, FftNorm::Backward, &mut backend)
        .unwrap_err();
    let shape_err = spectrum
        .irfft(Some(6), -1, FftNorm::Backward, &mut backend)
        .unwrap_err();

    assert!(matches!(
        dtype_err,
        tenferro_tensor::Error::InvalidConfig {
            op: "TensorFftExt::fft",
            ..
        }
    ));
    assert!(matches!(
        shape_err,
        tenferro_tensor::Error::InvalidConfig { op: "irfft", .. }
    ));
}