nalgebra/src/sparse/cs_utils.rs

use allocator::Allocator;
use {DefaultAllocator, Dim, VectorN};

pub fn cumsum<D: Dim>(a: &mut VectorN<usize, D>, b: &mut VectorN<usize, D>) -> usize
where DefaultAllocator: Allocator<usize, D> {
    assert!(a.len() == b.len());
    let mut sum = 0;

    for i in 0..a.len() {
        b[i] = sum;
        sum += a[i];
        a[i] = b[i];
    }

    sum
}