Use formulas for periodic windows

[wizenink]

I was using the symettric window functions instead of periodic, which introduced some ripple and caused COLA violations to trigger for perfectly valid COLA configurations

[gemini-code-assist]

Summary of Changes

Hello @wizenink, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request fixes a bug in the generate_window function where certain window types (Hann, Hamming, Blackman) were incorrectly calculated using symmetric window formulas instead of periodic ones. By switching to the correct periodic formulas, the change resolves false COLA violations, ensuring that signal processing operations behave as expected with valid configurations.

Highlights

• Corrected Window Function Formulas: The formulas for Hann, Hamming, and Blackman window types in the generate_window function were updated to use the periodic window calculation, specifically dividing by the window size N instead of N-1.
• Resolved COLA Violations: This correction addresses an issue where the use of symmetric window functions instead of periodic ones was causing Constant Overlap-Add (COLA) violations to trigger for configurations that should have been valid.

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[gemini-code-assist]

Code Review

The pull request correctly updates the window functions to use periodic formulas instead of symmetric ones, which resolves the COLA violation issues. I've added a few suggestions to improve performance by moving constant calculations out of the loops within the generate_window function. These changes will make the code more efficient.

[gemini-code-assist]

Similar to the Hann window, constant values can be calculated outside the map closure for better performance. Also, using named constants for magic numbers like 0.54 and 0.46 improves readability.

        WindowType::Hamming => {
            let size_t = T::from(size).unwrap(); // Use N, not N-1 for periodic window
            let a0 = T::from(0.54).unwrap();
            let a1 = T::from(0.46).unwrap();
            (0..size)
                .map(|i| {
                    let i_t = T::from(i).unwrap();
                    a0 - a1 * (two * pi * i_t / size_t).cos()
                })
                .collect()
        },