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use std::cmp::max;
pub fn sigscale(val: f64, sf: usize) -> (f64, usize) {
if val.is_normal() {
let sf = sf as i32;
let log = val.abs().log10();
let mut scale = log.ceil() as i32;
if log == log.ceil() {
scale = scale + 1;
}
let scale_diff = sf - scale;
let adj = 10.0f64.powi(scale_diff);
let adj_val = (val * adj).round() / adj;
(adj_val, max(scale_diff, 0) as usize)
} else {
(val, sf)
}
}
#[test]
fn test_zero() {
let (v, prec) = sigscale(0.0, 4);
assert_eq!(v, 0.0);
assert_eq!(prec, 4);
}
#[test]
fn test_one() {
let (v, prec) = sigscale(1.0, 4);
assert_eq!(v, 1.0);
assert_eq!(prec, 3);
}
#[test]
fn test_two_digits() {
let (v, prec) = sigscale(15.3234, 4);
assert_eq!(v, 15.32);
assert_eq!(prec, 2);
}
#[test]
fn test_small() {
let (v, prec) = sigscale(0.000315772, 2);
assert_eq!(v, 0.00032);
assert_eq!(prec, 5);
}