mrrs 0.1.1

Multi rate filtering tools
Documentation 
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use num_traits::{Float, FromPrimitive};
pub mod naive;
#[cfg(feature = "python")]
pub mod py;

fn get_hb_filter_half_remez<T: Float + FromPrimitive>(ntaps: usize) -> Vec<T> {
    if ntaps == 8 {
        return vec![
            T::from(-0.005476842557111799).expect("constant"),
            T::from(0.007835118218077888).expect("constant"),
            T::from(-0.013294204112335284).expect("constant"),
            T::from(0.02139788621711558).expect("constant"),
            T::from(-0.03380624136244843).expect("constant"),
            T::from(0.054873461629305925).expect("constant"),
            T::from(-0.1006411645771518).expect("constant"),
            T::from(0.3164568033034065).expect("constant"),
        ];
    }
    todo!("Add support for ntaps={}", ntaps);
}

#[allow(dead_code)]
pub fn get_hb_filter<T: Float + FromPrimitive>(ntaps: usize) -> Vec<T> {
    assert_eq!((ntaps - 1) % 2, 0);
    assert_ne!((ntaps - 1) % 4, 0);
    let half_remez = get_hb_filter_half_remez::<T>((ntaps + 1) / 4);
    let mut full = vec![];
    for ii in 0..half_remez.len() - 1 {
        full.push(half_remez[ii]);
        full.push(T::zero());
    }
    full.push(half_remez[half_remez.len() - 1]);
    full.push(T::from(0.5).expect("constant"));
    for ii in (1..half_remez.len()).rev() {
        full.push(half_remez[ii]);
        full.push(T::zero());
    }
    full.push(half_remez[0]);
    full
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_hb_flt_properties() {
        let flt = get_hb_filter::<f64>(31);
        assert_eq!(flt.len(), 31);
        assert_eq!(flt[0], -0.005476842557111799);
        assert_eq!(flt[2], 0.007835118218077888);
        assert_eq!(flt[4], -0.013294204112335284);
        assert_eq!(flt[6], 0.02139788621711558);
        assert_eq!(flt[8], -0.03380624136244843);
        assert_eq!(flt[10], 0.054873461629305925);
        assert_eq!(flt[12], -0.1006411645771518);
        assert_eq!(flt[14], 0.3164568033034065);
        assert_eq!(flt[flt.len() / 2], 0.5);
        for ii in 0..(flt.len() / 2 - 1) {
            assert_eq!(flt[ii], flt[flt.len() - ii - 1]);
            if ii % 2 == 1 {
                assert_eq!(flt[ii], 0.0);
            }
        }
    }
}