Function modwt_level_into 

pub fn modwt_level_into<T: SignalType>(
    data: &[T],
    wavelet: &dyn Wavelet,
    level: usize,
    wavelet_out: &mut Vec<T>,
    scaling_out: &mut Vec<T>,
) -> Result<()>

Single-level MODWT with filter dilation, writing into caller-supplied output buffers.

At level == 0 this is equivalent to modwt_into; for level > 0 the analysis filters are dilated by 2^level. Dispatches to the SIMD-vectorized modwt_convolve_bulk_into kernel (pulp AVX2/NEON/scalar dispatch + short-filter Haar/Db2 fast path) while writing directly into the caller-supplied output buffers.