Fix a negative underflow when calculating quantiles

Fixes #5.
2017-11-19 10:31:00 +01:00 · 2017-11-19 10:31:00 +01:00 · 5656156660
commit 5656156660
parent 57f9d13434
1 changed files with 3 additions and 3 deletions
--- a/src/quantile.rs
+++ b/src/quantile.rs
@ -60,9 +60,9 @@ impl Quantile {
    #[inline]
    fn linear(&self, i: usize, d: f64) -> f64 {
        debug_assert_eq!(d.abs(), 1.);
-        let s: usize = d.approx().unwrap();
-        self.q[i] + d * (self.q[i + s] - self.q[i])
-            / f64::approx_from(self.n[i + s] - self.n[i]).unwrap()
+        let sum = if d < 0. { i - 1 } else { i + 1 };
+        self.q[i] + d * (self.q[sum] - self.q[i])
+            / f64::approx_from(self.n[sum] - self.n[i]).unwrap()
    }

    /// Estimate the p-quantile of the population.