Struct rustfft::algorithm::GoodThomasAlgorithmDoubleButterfly [−][src]
pub struct GoodThomasAlgorithmDoubleButterfly<T> { /* fields omitted */ }
Implementation of the Good-Thomas Algorithm, specialized for the case where both inner FFTs are butterflies
This algorithm factors a size n FFT into n1 * n2, where GCD(n1, n2) == 1
Conceptually, this algorithm is very similar to the Mixed-Radix FFT, except because GCD(n1, n2) == 1 we can do some number theory trickery to reduce the number of floating-point multiplications and additions. It typically performs better than Mixed-Radix Double Butterfly Algorithm, especially at small sizes.
// Computes a forward FFT of size 56, using the Good-Thoma Butterfly Algorithm use std::sync::Arc; use rustfft::algorithm::GoodThomasAlgorithmDoubleButterfly; use rustfft::algorithm::butterflies::{Butterfly7, Butterfly8}; use rustfft::FFT; use rustfft::num_complex::Complex; use rustfft::num_traits::Zero; let mut input: Vec<Complex<f32>> = vec![Zero::zero(); 56]; let mut output: Vec<Complex<f32>> = vec![Zero::zero(); 56]; // we need to find an n1 and n2 such that n1 * n2 == 56 and GCD(n1, n2) == 1 // n1 = 7 and n2 = 8 satisfies this let inner_fft_n1 = Arc::new(Butterfly7::new(false)); let inner_fft_n2 = Arc::new(Butterfly8::new(false)); // the good-thomas FFT length will be inner_fft_n1.len() * inner_fft_n2.len() = 56 let fft = GoodThomasAlgorithmDoubleButterfly::new(inner_fft_n1, inner_fft_n2); fft.process(&mut input, &mut output);
Methods
impl<T: FFTnum> GoodThomasAlgorithmDoubleButterfly<T>
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impl<T: FFTnum> GoodThomasAlgorithmDoubleButterfly<T>
pub fn new(
width_fft: Arc<FFTButterfly<T>>,
height_fft: Arc<FFTButterfly<T>>
) -> Self
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pub fn new(
width_fft: Arc<FFTButterfly<T>>,
height_fft: Arc<FFTButterfly<T>>
) -> Self
Creates a FFT instance which will process inputs/outputs of size width_fft.len() * height_fft.len()
GCD(n1.len(), n2.len()) must be equal to 1
Trait Implementations
impl<T: FFTnum> FFT<T> for GoodThomasAlgorithmDoubleButterfly<T>
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impl<T: FFTnum> FFT<T> for GoodThomasAlgorithmDoubleButterfly<T>
fn process(&self, input: &mut [Complex<T>], output: &mut [Complex<T>])
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fn process(&self, input: &mut [Complex<T>], output: &mut [Complex<T>])
Computes an FFT on the input
buffer and places the result in the output
buffer. Read more
fn process_multi(&self, input: &mut [Complex<T>], output: &mut [Complex<T>])
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fn process_multi(&self, input: &mut [Complex<T>], output: &mut [Complex<T>])
Divides the input
and output
buffers into chunks of length self.len(), then computes an FFT on each chunk. Read more
impl<T> Length for GoodThomasAlgorithmDoubleButterfly<T>
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impl<T> Length for GoodThomasAlgorithmDoubleButterfly<T>
impl<T> IsInverse for GoodThomasAlgorithmDoubleButterfly<T>
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impl<T> IsInverse for GoodThomasAlgorithmDoubleButterfly<T>
fn is_inverse(&self) -> bool
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fn is_inverse(&self) -> bool
Returns false if this instance computes forward FFTs, true for inverse FFTs
Auto Trait Implementations
impl<T> Send for GoodThomasAlgorithmDoubleButterfly<T>
impl<T> Send for GoodThomasAlgorithmDoubleButterfly<T>
impl<T> Sync for GoodThomasAlgorithmDoubleButterfly<T>
impl<T> Sync for GoodThomasAlgorithmDoubleButterfly<T>