#1164 Make ApproxF64 also have approximate ordering

base/src/approx_f64.rs

@@ -1,3 +1,4 @@
+use std::cmp::Ordering;
 use std::fmt::{Display, Formatter};
 
 /// An approximate floating-point type that uses the same epsilon for comparison as the == operator in
@@ -9,7 +10,7 @@ pub type AudioF64 = ApproxF64<100000>;
 ///
 /// The const type parameter `E` ("epsilon") defines how tolerant floating-point comparison is. Two values are considered
 /// equal if the difference is less than 1/E.
-#[derive(Copy, Clone, PartialOrd, Debug, Default)]
+#[derive(Copy, Clone, Debug, Default)]
 pub struct ApproxF64<const E: u32>(pub f64);
 
 impl<const E: u32> ApproxF64<E> {
@@ -18,11 +19,24 @@ impl<const E: u32> ApproxF64<E> {
     pub fn new(raw: f64) -> Self {
         Self(raw)
     }
+
+    fn difference_is_neglectable(&self, other: &Self) -> bool {
+        (self.0 - other.0).abs() < Self::EPSILON
+    }
+}
+
+impl<const E: u32> PartialOrd for ApproxF64<E> {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if self.difference_is_neglectable(other) {
+            return Some(Ordering::Equal);
+        }
+        self.0.partial_cmp(&other.0)
+    }
 }
 
 impl<const E: u32> PartialEq for ApproxF64<E> {
     fn eq(&self, other: &Self) -> bool {
-        (self.0 - other.0).abs() < Self::EPSILON
+        self.difference_is_neglectable(other)
     }
 }