diff --git a/Cargo.toml b/Cargo.toml
index 4a64b25..83b29bc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,4 +10,3 @@ statrs = "0.10"
 
 [dev-dependencies]
 approx = "0.3"
-env_logger = "0.6"
diff --git a/src/gaussian.rs b/src/gaussian.rs
index 53462b4..2e24135 100644
--- a/src/gaussian.rs
+++ b/src/gaussian.rs
@@ -8,7 +8,7 @@ pub struct Gaussian {
 }
 
 impl fmt::Debug for Gaussian {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
             "N(mu={:.03}, sigma={:.03}, pi={:.03}, tau={:.03})",
diff --git a/src/lib.rs b/src/lib.rs
index 0fcc512..af50db1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,5 @@
 #![allow(clippy::unreadable_literal, clippy::excessive_precision)]
+#![warn(rust_2018_idioms)]
 
 mod factor_graph;
 mod gaussian;
@@ -108,12 +109,12 @@ fn draw_margin(p: f64, beta: f64, total_players: f64) -> f64 {
 }
 
 pub struct TrueSkill {
-    mu: f64,
-    sigma: f64,
+    // mu: f64,
+    // sigma: f64,
     pub beta: f64,
     pub tau: f64,
     pub draw_probability: f64,
-    delta: f64,
+    // delta: f64,
 }
 
 impl TrueSkill {
@@ -357,12 +358,12 @@ impl TrueSkill {
 impl Default for TrueSkill {
     fn default() -> TrueSkill {
         TrueSkill {
-            mu: MU,
-            sigma: SIGMA,
+            // mu: MU,
+            // sigma: SIGMA,
             beta: BETA,
             tau: TAU,
             draw_probability: DRAW_PROBABILITY,
-            delta: DELTA,
+            // delta: DELTA,
         }
     }
 }
@@ -370,7 +371,6 @@ impl Default for TrueSkill {
 #[cfg(test)]
 mod tests {
     use approx::*;
-    use env_logger;
 
     use super::*;
 
diff --git a/src/matrix.rs b/src/matrix.rs
index 4448ec2..bbb76d5 100644
--- a/src/matrix.rs
+++ b/src/matrix.rs
@@ -115,6 +115,7 @@ impl Matrix {
         if self.height == self.width && self.height == 1 {
             matrix[(0, 0)] = 1.0 / self[(0, 0)];
         } else {
+
         }
 
         matrix