fn main() {
    //given these:
    let srcs:Vec<Vec<f32>> = vec![
        (1..9).map(|v| v as f32).collect(),
        (101..109).map(|v| v as f32).collect()
    ];

    let mut dest = [0.0f32; 16];

    println!("srcs[0] before: {:?}", srcs[0]);
    println!("srcs[1] before: {:?}", srcs[1]);
    println!("dest before: {:?}", dest);

    //write
    write_to_slice(&srcs, &mut dest);

    //it's all there :)
    println!("dest after: {:?}", dest);
}

fn write_to_slice(srcs:&[Vec<f32>], dest:&mut [f32]) {
    let mut offset = 0;
    for src in srcs.iter() {
        for (index, value) in src.iter().enumerate() {
           dest[index + offset] = *value;
        }
        offset += src.len();
    }
}