---

yaml
---
r: 94141
b: refs/heads/try
c: 705b705
h: refs/heads/master
i:
  94139: 9380b90
v: v3

Author: huonw

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: 0da105a8b7b6b1e0568e8ff20f6ff4b13cc7ecc2
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: a6d3e57dca68fde4effdda3e4ae2887aa535fcd6
-refs/heads/try: 6155a1c98012f9565744dad3832660accd135b83
+refs/heads/try: 705b705ba5182745e12652dc7eeeb10828f520d0
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
 refs/heads/try2: 147ecfdd8221e4a4d4e090486829a06da1e0ca3c

branches/try/src/libstd/rand/distributions/gamma.rs

@@ -274,6 +274,47 @@ impl IndependentSample<f64> for FisherF {
     }
 }
 
+/// The Student t distribution, `t(nu)`, where `nu` is the degrees of
+/// freedom.
+///
+/// # Example
+///
+/// ```rust
+/// use std::rand;
+/// use std::rand::distributions::{StudentT, IndependentSample};
+///
+/// fn main() {
+///     let t = StudentT::new(11.0);
+///     let v = t.ind_sample(&mut rand::task_rng());
+///     println!("{} is from a t(11) distribution", v)
+/// }
+/// ```
+pub struct StudentT {
+    priv chi: ChiSquared,
+    priv dof: f64
+}
+
+impl StudentT {
+    /// Create a new Student t distribution with `n` degrees of
+    /// freedom. Fails if `n <= 0`.
+    pub fn new(n: f64) -> StudentT {
+        assert!(n > 0.0, "StudentT::new called with `n <= 0`");
+        StudentT {
+            chi: ChiSquared::new(n),
+            dof: n
+        }
+    }
+}
+impl Sample<f64> for StudentT {
+    fn sample<R: Rng>(&mut self, rng: &mut R) -> f64 { self.ind_sample(rng) }
+}
+impl IndependentSample<f64> for StudentT {
+    fn ind_sample<R: Rng>(&self, rng: &mut R) -> f64 {
+        let norm = *rng.gen::<StandardNormal>();
+        norm * (self.dof / self.chi.ind_sample(rng)).sqrt()
+    }
+}
+
 #[cfg(test)]
 mod test {
     use rand::*;
@@ -323,6 +364,16 @@ mod test {
             f.ind_sample(&mut rng);
         }
     }
+
+    #[test]
+    fn test_t() {
+        let mut t = StudentT::new(11.0);
+        let mut rng = task_rng();
+        for _ in range(0, 1000) {
+            t.sample(&mut rng);
+            t.ind_sample(&mut rng);
+        }
+    }
 }
 
 #[cfg(test)]

branches/try/src/libstd/rand/distributions/mod.rs

@@ -27,7 +27,7 @@ use rand::{Rng, Rand};
 use clone::Clone;
 
 pub use self::range::Range;
-pub use self::gamma::{Gamma, ChiSquared, FisherF};
+pub use self::gamma::{Gamma, ChiSquared, FisherF, StudentT};
 pub use self::normal::{Normal, LogNormal};
 pub use self::exponential::Exp;