Crate microfft[−][src]
Library for computing fast fourier transforms on embedded systems.
microfft provides an in-place implementation of the Radix-2 FFT algorithm.
All computations are performed directly on the input buffer and require no
additional allocations. This makes microfft suitable for no_std
environments.
In addition to the standard FFT implementation on Complex32
values
(complex
), an implementation working on real (f32
) input values is
provided (real
). An N
-point RFFT internally computes an N/2
-point
CFFT, making it roughly twice as fast as the complex variant.
Example
use std::convert::TryInto; use std::f32::consts::PI; // generate 16 samples of a sine wave at frequency 3 let sample_count = 16; let signal_freq = 3.; let sample_interval = 1. / sample_count as f32; let mut samples: Vec<_> = (0..sample_count) .map(|i| (2. * PI * signal_freq * sample_interval * i as f32).sin()) .collect(); // compute the RFFT of the samples let mut samples: [_; 16] = samples.try_into().unwrap(); let spectrum = microfft::real::rfft_16(&mut samples); // since the real-valued coefficient at the Nyquist frequency is packed into the // imaginary part of the DC bin, it must be cleared before computing the amplitudes spectrum[0].im = 0.0; // the spectrum has a spike at index `signal_freq` let amplitudes: Vec<_> = spectrum.iter().map(|c| c.norm_sqr() as u32).collect(); assert_eq!(&litudes, &[0, 0, 0, 64, 0, 0, 0, 0]);
Modules
complex | FFT on complex inputs (CFFT) |
real | FFT on real inputs (RFFT) |
Type Definitions
Complex32 |