1use crate::{Encoding, VecZnx, ZnxInfos};
 2use rug::Float;
 3use rug::float::Round;
 4use rug::ops::{AddAssignRound, DivAssignRound, SubAssignRound};
 5
 6impl VecZnx {
 7    pub fn std(&self, poly_idx: usize, log_base2k: usize) -> f64 {
 8        let prec: u32 = (self.cols() * log_base2k) as u32;
 9        let mut data: Vec<Float> = (0..self.n()).map(|_| Float::with_val(prec, 0)).collect();
10        self.decode_vec_float(poly_idx, log_base2k, &mut data);
11        // std = sqrt(sum((xi - avg)^2) / n)
12        let mut avg: Float = Float::with_val(prec, 0);
13        data.iter().for_each(|x| {
14            avg.add_assign_round(x, Round::Nearest);
15        });
16        avg.div_assign_round(Float::with_val(prec, data.len()), Round::Nearest);
17        data.iter_mut().for_each(|x| {
18            x.sub_assign_round(&avg, Round::Nearest);
19        });
20        let mut std: Float = Float::with_val(prec, 0);
21        data.iter().for_each(|x| std += x * x);
22        std.div_assign_round(Float::with_val(prec, data.len()), Round::Nearest);
23        std = std.sqrt();
24        std.to_f64()
25    }
26}