This crate provides functions for computing the Hann window, a function used to taper the edges of a signal window to reduce spectral leakage. The Hann window is defined by the formula w(n) = 0.5 - 0.5 * cos(2π * n / (N - 1)), where n is the index of the current sample and N is the length of the window.

A lookup table for pre-computed Hann windows is provided for common window lengths. This improves performance for repeated calculations with the same window length.

1. Import the crate:

[dependencies]
hann-rs = "0.1.0"

use hann_rs::get_hann_window;

2. Get a Hann window of a specific length using the get_hann_window function:

let window_length = 1024;
let hann_window = get_hann_window(window_length).expect("Failed to get the Hann window");

If the desired window length is in the lookup table, the precomputed values will be returned. If not, the Hann window values will be computed.

The lookup table, HANN_WINDOW_LOOKUP_TABLE, contains precomputed Hann windows of lengths 256, 512, 1024, 2048, and 4096.

You can add or modify the precomputed window lengths by changing the HANN_WINDOW_PRECOMPUTED_LENGTHS array in the lazy_static block:

const HANN_WINDOW_PRECOMPUTED_LENGTHS: [usize; 5] = [256, 512, 1024, 2048, 4096];

The functions get_hann_window return a Result<Vec<f32>, HannWindowError> type. Errors are returned in the following cases:

• The window length is less than or equal to 1.
• The window length is greater than the allowed maximum.
• Memory allocation errors due to a large window length.

To handle these errors, use the Result type as follows:

match get_hann_window(window_length) {
    Ok(hann_window) => {
        // Use the Hann window
    },
    Err(error) => {
        println!("Error getting the Hann window: {:?}", error);
        // or handle the error in your way
    },
}

This module provides functions for computing the sum of squares of a Hann window. It utilizes a lookup table for pre-computed sum of squares for common Hann window lengths, improving performance for repeated calculations with the same window length.

1. Import the module:

use hann_rs::get_hann_window_sum_squares;

2. Get the sum of squares of a Hann window using the get_hann_window_sum_squares function:

let hann_window: Vec<f32> = vec![...]; // The Hann window values
let hann_window_sum_squares = get_hann_window_sum_squares(&hann_window);

If the length of the input hann_window is in the lookup table, the precomputed value will be returned. If not, the sum of squares will be computed using map and sum.

The lookup table, HANN_WINDOW_SUM_OF_SQUARES, contains precomputed sum of squares for Hann windows of lengths 256, 512, 1024, 2048, and 4096.

You can add or modify the precomputed window lengths by changing the HANN_WINDOW_PRECOMPUTED_LENGTHS array in the lazy_static block:

const HANN_WINDOW_PRECOMPUTED_LENGTHS: [usize; 5] = [256, 512, 1024, 2048, 4096];