feat: f32/f64 cargo features added

Signed-off-by: Stephen Waits <steve@waits.net>

Cargo.toml

@@ -1,9 +1,9 @@
 [package]
 name = "vivaldi-nc"
-version = "0.4.1"
+version = "0.5.2"
 edition = "2021"
 authors = ["Stephen Waits <steve@waits.net>"]
-description = "Vivaldi network coordinates with a simple interface."
+description = "Vivaldi network coordinates for fast, distributed latency estimates in multinode networks, with a clean and simple interface."
 license = "MIT"
 keywords = ["vivaldi", "network", "coordinates", "distributed", "p2p"]
 categories = ["algorithms", "network-programming"]
@@ -15,6 +15,11 @@ exclude = [
 	"examples/*",
 ]
 
+[features]
+default = ["f32"]
+f32 = []
+f64 = []
+
 [dev-dependencies]
 assert_approx_eq = "1.1.0"
 proptest = "1.0.0"

README.md

@@ -110,28 +110,49 @@ and compact binary formats like [bincode](https://crates.io/crates/bincode) and
 See the [module documentation](https://docs.rs/vivaldi-nc) for more detailed
 usage examples.
 
+### Cargo Features
+
+By default, the internal data structures and operations all use `f32`. If you want to use `f64`, you can enable it as a cargo feature:
+
+```toml
+[dependencies]
+vivaldi-nc = { version = "0.5.2", features = ["f64"] }
+```
+
 ### Examples
 
 The repository includes an example which loads a n-to-n latency sample from
 PlanetLab and iterates on `NetworkCoordinate`s until some low-enough mean error
-is reached. The output is a JSON array of elements that look like this:
+is reached. The output is a JSON array of elements which contain the NC's
+position, its height (or stem latency estimate), and its estimation of error
+(lower is better) that look like this:
 
 ```json
-  {
+{
-    "position": [
+  "position": [
-      {
+    5.563593,
-        "inner": [     # Euclidean position (3D in this case):
+    -2.332495,
-          9.249476,      # first dimension; "x"
+    7.3957834
-          23.747225,     # second dimension; "x"
+  ],
-          -6.473008      # third dimension; "x"
+  "height": 55.56651,
-        ]
+  "error": 3.241348
-      },
+}
-      72.10599         # Height component (estimate of stem latency in milliseconds)
-    ],
-    "error": 2.9166403 # Estimated error (lower is better)
-  },
-
 ```
+Adding some detail to these three fields:
+
+- `position`: Estimated position of this node (or `NetworkCoordinate`) on the
+  network core. Think of this like the node's endpoint into the Internet
+  backbone. This is a cartesian coordinate in a multi-dimensional latency space
+  (in this case 3D), measured in milliseconds.
+- `height`: Estimated stem time, which is the time from the node itself to the
+  backbone. So, for example this might represent the latency between your
+  node's actual location, like your home, and the point at which it gets into
+  the highest-speed, core part of the Internet. Height helps adjust for
+  [triangle inequality violations](https://en.wikipedia.org/wiki/Triangle_inequality),
+  which are common on the Internet.
+- `error`: Estimated error of the current `position`, and `height`. Lower is
+  better.
+
 To run the example, first clone the repository locally:
 
 ```bash

src/height_vector.rs

@@ -49,6 +49,15 @@ use serde::{Deserialize, Serialize};
 
 use crate::vector::Vector;
 
+//
+// **** Features ****
+//
+#[cfg(feature = "f32")]
+type FloatType = f32;
+
+#[cfg(feature = "f64")]
+type FloatType = f64;
+
 //
 // **** Constants ****
 //
@@ -63,7 +72,11 @@ use crate::vector::Vector;
 ///
 /// - `N`: the dimensionality of the vector portion (i.e. non-height) of the Vivaldi height vector
 #[derive(Copy, Clone, Debug, Serialize, Deserialize)]
-pub(crate) struct HeightVector<const N: usize>(Vector<f32, N>, f32);
+pub(crate) struct HeightVector<const N: usize> {
+    #[serde(flatten)]
+    position: Vector<FloatType, N>,
+    height: FloatType,
+}
 
 //
 // **** Implementations ****
@@ -80,28 +93,35 @@ impl<const N: usize> HeightVector<N> {
         let mut rng = WyRand::new();
         let mut vec = [0.0; N];
         for i in vec.iter_mut().take(N) {
-            *i = rng.generate::<f32>();
+            *i = rng.generate::<FloatType>();
         }
-        let height = rng.generate::<f32>().abs();
+        let height = rng.generate::<FloatType>().abs();
-        Self(Vector::<f32, N>::from(vec), height).normalized()
+        Self {
+            position: Vector::<FloatType, N>::from(vec),
+            height,
+        }
+        .normalized()
     }
 
     /// The magnitude of a Vivaldi height vector is defined as the magnitude of the vector plus the
     /// height value.
-    pub(crate) fn len(&self) -> f32 {
+    pub(crate) fn len(&self) -> FloatType {
-        self.0.len() + self.1
+        self.position.len() + self.height
     }
 
     /// A normalized Vivaldi height vector is just like a normalized vector: the vector scaled
     /// by the inveerse of its length.
     pub(crate) fn normalized(&self) -> Self {
         let len = self.len();
-        if len < f32::EPSILON {
+        if len < FloatType::EPSILON {
             // if we have a bad vector, generate a new random vector
             Self::new()
         } else {
             // otherwise scale it by the inverse of its magnitude like any normal vector
-            Self(self.0 / len, self.1 / len)
+            Self {
+                position: self.position / len,
+                height: self.height / len,
+            }
         }
     }
 
@@ -118,7 +138,10 @@ impl<const N: usize> HeightVector<N> {
     /// In this case, valid means the height is positive, and none of the components are NaN or
     /// Inf.
     pub(crate) fn is_invalid(&self) -> bool {
-        self.0.is_invalid() || self.1.is_nan() || self.1.is_infinite() || self.1 < 0.0
+        self.position.is_invalid()
+            || self.height.is_nan()
+            || self.height.is_infinite()
+            || self.height < 0.0
     }
 }
 
@@ -129,14 +152,20 @@ impl<const N: usize> HeightVector<N> {
 impl<const N: usize> Default for HeightVector<N> {
     /// Default value for a Vivaldi height vector is just the defaults of its children types.
     fn default() -> Self {
-        Self(Default::default(), Default::default())
+        Self {
+            position: Default::default(),
+            height: Default::default(),
+        }
     }
 }
 
-impl<const N: usize> From<([f32; N], f32)> for HeightVector<N> {
+impl<const N: usize> From<([FloatType; N], FloatType)> for HeightVector<N> {
-    /// Convert from a `([f32; N], f32)` (vector, height) to a Vivaldi height vector type.
+    /// Convert from a `([FloatType; N], FloatType)` (vector, height) to a Vivaldi height vector type.
-    fn from(value: ([f32; N], f32)) -> Self {
+    fn from(value: ([FloatType; N], FloatType)) -> Self {
-        let ret = Self(Vector::<f32, N>::from(value.0), value.1);
+        let ret = Self {
+            position: Vector::<FloatType, N>::from(value.0),
+            height: value.1,
+        };
         if ret.is_valid() {
             ret
         } else {
@@ -150,7 +179,10 @@ impl<const N: usize> Add for HeightVector<N> {
 
     /// Add two Vivaldi height vectors.
     fn add(self, rhs: Self) -> Self::Output {
-        let ret = Self(self.0 + rhs.0, self.1 + rhs.1);
+        let ret = Self {
+            position: self.position + rhs.position,
+            height: self.height + rhs.height,
+        };
         if ret.is_valid() {
             ret
         } else {
@@ -165,7 +197,10 @@ impl<const N: usize> Sub for HeightVector<N> {
     /// Subtract two Vivaldi height vectors. Note that this is the difference in the vectors
     /// and the summation of the heights, as defined by Vivaldi's author.
     fn sub(self, rhs: Self) -> Self::Output {
-        let ret = Self(self.0 - rhs.0, self.1 + rhs.1);
+        let ret = Self {
+            position: self.position - rhs.position,
+            height: self.height + rhs.height,
+        };
         if ret.is_valid() {
             ret
         } else {
@@ -174,12 +209,15 @@ impl<const N: usize> Sub for HeightVector<N> {
     }
 }
 
-impl<const N: usize> Mul<f32> for HeightVector<N> {
+impl<const N: usize> Mul<FloatType> for HeightVector<N> {
     type Output = Self;
 
     /// Multiply a Vivaldi height vector by a scalar. Works the same as normal vector scaling.
-    fn mul(self, rhs: f32) -> Self::Output {
+    fn mul(self, rhs: FloatType) -> Self::Output {
-        let ret = Self(self.0 * rhs, self.1 * rhs);
+        let ret = Self {
+            position: self.position * rhs,
+            height: self.height * rhs,
+        };
         if ret.is_valid() {
             ret
         } else {
@@ -199,7 +237,7 @@ mod tests {
 
     proptest! {
         #[test]
-        fn proptest_len(x: f32, y: f32, h: f32) {
+        fn proptest_len(x: FloatType, y: FloatType, h: FloatType) {
             let len = ((x*x) + (y*y)).sqrt() + h.abs();
             let a = HeightVector::<2>::from(([x,y],h));
             if x.is_nan() || x.is_infinite() || y.is_nan() || y.is_infinite() || h.is_nan() || h.is_infinite() || h < 0.0 {
@@ -213,45 +251,45 @@ mod tests {
 
         #[test]
         fn proptest_add(x0 in -1_000_000_000..1_000_000_000i32, y0 in -1_000_000_000..1_000_000_000i32, h0 in 0..1_000_000_000i32, x1 in -1_000_000_000..1_000_000_000i32, y1 in -1_000_000_000..1_000_000_000i32, h1 in 0..1_000_000i32) {
-            // convert our integer range inputs to f32s
+            // convert our integer range inputs to FloatType
-            let (fx0,fy0,fh0) = (x0 as f32 / 1_000.0, y0 as f32 / 1_000.0, h0 as f32 / 1_000.0);
+            let (fx0,fy0,fh0) = (x0 as FloatType / 1_000.0, y0 as FloatType / 1_000.0, h0 as FloatType / 1_000.0);
-            let (fx1,fy1,fh1) = (x1 as f32 / 1_000.0, y1 as f32 / 1_000.0, h1 as f32 / 1_000.0);
+            let (fx1,fy1,fh1) = (x1 as FloatType / 1_000.0, y1 as FloatType / 1_000.0, h1 as FloatType / 1_000.0);
 
             let a = HeightVector::<2>::from(([fx0 ,fy0 ],fh0 ));
             let b = HeightVector::<2>::from(([fx1 ,fy1 ],fh1 ));
             let c = a+b;
-            assert_eq!(c.0[0], fx0 + fx1);
+            assert_eq!(c.position[0], fx0 + fx1);
-            assert_eq!(c.0[1], fy0 + fy1);
+            assert_eq!(c.position[1], fy0 + fy1);
-            assert_eq!(c.1, fh0 + fh1);
+            assert_eq!(c.height, fh0 + fh1);
         }
 
         #[test]
         fn proptest_sub(x0 in -1_000_000_000..1_000_000_000i32, y0 in -1_000_000_000..1_000_000_000i32, h0 in 0..1_000_000_000i32, x1 in -1_000_000_000..1_000_000_000i32, y1 in -1_000_000_000..1_000_000_000i32, h1 in 0..1_000_000i32) {
-            // convert our integer range inputs to f32s
+            // convert our integer range inputs to FloatType
-            let (fx0,fy0,fh0) = (x0 as f32 / 1_000.0, y0 as f32 / 1_000.0, h0 as f32 / 1_000.0);
+            let (fx0,fy0,fh0) = (x0 as FloatType / 1_000.0, y0 as FloatType / 1_000.0, h0 as FloatType / 1_000.0);
-            let (fx1,fy1,fh1) = (x1 as f32 / 1_000.0, y1 as f32 / 1_000.0, h1 as f32 / 1_000.0);
+            let (fx1,fy1,fh1) = (x1 as FloatType / 1_000.0, y1 as FloatType / 1_000.0, h1 as FloatType / 1_000.0);
 
             let a = HeightVector::<2>::from(([fx0 ,fy0 ],fh0 ));
             let b = HeightVector::<2>::from(([fx1 ,fy1 ],fh1 ));
             let c = a-b;
-            assert_eq!(c.0[0], fx0 - fx1);
+            assert_eq!(c.position[0], fx0 - fx1);
-            assert_eq!(c.0[1], fy0 - fy1);
+            assert_eq!(c.position[1], fy0 - fy1);
-            assert_eq!(c.1, fh0 + fh1);
+            assert_eq!(c.height, fh0 + fh1);
         }
 
         #[test]
         fn proptest_mul(x in -1_000_000_000..1_000_000_000i32, y in -1_000_000_000..1_000_000_000i32, h in 0..1_000_000_000i32, m in -1_000_000_000..1_000_000_000i32) {
-            // convert our integer range inputs to f32s
+            // convert our integer range inputs to FloatType
-            let (fx,fy,fh,fm) = (x as f32 / 1_000.0, y as f32 / 1_000.0, h as f32 / 1_000.0, m as f32 / 1_000.0);
+            let (fx,fy,fh,fm) = (x as FloatType / 1_000.0, y as FloatType / 1_000.0, h as FloatType / 1_000.0, m as FloatType / 1_000.0);
 
             let a = HeightVector::<2>::from(([fx, fy], fh));
             let b = a * fm;
             if fm < 0.0 {
                 assert_approx_eq!(b.len(), 1.0)
             } else {
-                assert_eq!(b.0[0], fx * fm);
+                assert_eq!(b.position[0], fx * fm);
-                assert_eq!(b.0[1], fy * fm);
+                assert_eq!(b.position[1], fy * fm);
-                assert_eq!(b.1, fh * fm);
+                assert_eq!(b.height, fh * fm);
             }
         }
     }
@@ -279,9 +317,9 @@ mod tests {
     #[test]
     fn test_from() {
         let a = HeightVector::<2>::from(([1.0, 2.0], 3.0));
-        assert_eq!(a.0[0], 1.0);
+        assert_eq!(a.position[0], 1.0);
-        assert_eq!(a.0[1], 2.0);
+        assert_eq!(a.position[1], 2.0);
-        assert_eq!(a.1, 3.0);
+        assert_eq!(a.height, 3.0);
     }
 
     #[test]
@@ -289,9 +327,9 @@ mod tests {
         let a = HeightVector::<2>::from(([1.0, 2.0], 3.0));
         let b = HeightVector::<2>::from(([3.0, 2.0], 1.0));
         let c = a + b;
-        assert_eq!(c.0[0], 4.0);
+        assert_eq!(c.position[0], 4.0);
-        assert_eq!(c.0[1], 4.0);
+        assert_eq!(c.position[1], 4.0);
-        assert_eq!(c.1, 4.0);
+        assert_eq!(c.height, 4.0);
     }
 
     #[test]
@@ -299,23 +337,23 @@ mod tests {
         let a = HeightVector::<2>::from(([1.0, 2.0], 3.0));
         let b = HeightVector::<2>::from(([3.0, 2.0], 1.0));
         let c = a - b;
-        assert_eq!(c.0[0], -2.0);
+        assert_eq!(c.position[0], -2.0);
-        assert_eq!(c.0[1], 0.0);
+        assert_eq!(c.position[1], 0.0);
-        assert_eq!(c.1, 4.0);
+        assert_eq!(c.height, 4.0);
     }
 
     #[test]
     fn test_mul_scalar() {
         let a = HeightVector::<2>::from(([1.0, 2.0], 3.0)) * 10.0;
-        assert_eq!(a.0[0], 10.0);
+        assert_eq!(a.position[0], 10.0);
-        assert_eq!(a.0[1], 20.0);
+        assert_eq!(a.position[1], 20.0);
-        assert_eq!(a.1, 30.0);
+        assert_eq!(a.height, 30.0);
     }
 
     #[test]
     fn test_serde() {
         // start with JSON, deserialize it
-        let s = "[{\"inner\":[1.0,2.0,3.0]},4.0]";
+        let s = "{\"position\":[1.0,2.0,3.0],\"height\":4.0}";
         let a: HeightVector<3> = serde_json::from_str(s).unwrap();
 
         // make sure it's the right length and works like we expect a normal NC

src/lib.rs

@@ -1,4 +1,5 @@
-//! Vivaldi Network Coordinates with a simple interface
+//! Vivaldi network coordinates for fast, distributed latency estimates in multinode networks, with
+//! a clean and simple interface.
 //!
 //! Network Coordinates (NC) are a way to represent a node's position in a network's
 //! latency space. Nodes with low latency (ping or round trip time) between each
@@ -19,7 +20,8 @@
 //!
 //! # Usage
 //!
-//! This crate exports a single struct, [`NetworkCoordinate`]. Typical use of Vivaldi NCs for a
+//! This crate exports a single struct, [`NetworkCoordinate`] and two type aliases
+//! ([`NetworkCoordinate2D`] and [`NetworkCoordinate3D`]). Typical use of Vivaldi NCs for a
 //! distributed network works like this:
 //!
 //! 1. Each node in the network has its own instance of [`NetworkCoordinate`]. *See "Note on
@@ -51,7 +53,7 @@
 //!
 //! // mock up a remote NC for the sake of this example (normally the node would actually receive
 //! // this from a remote node)
-//! let received_msg = "{\"position\":[{\"inner\":[1.5,0.5,2.0]},0.1],\"error\":1.0}";
+//! let received_msg = "{\"position\":[1.5,0.5,2.0],\"height\":0.1,\"error\":1.0}";
 //! let remote_nc: NetworkCoordinate<3> = serde_json::from_str(received_msg).unwrap();
 //!
 //! // mock up a measured RTT between us and that node (normally the nodes would coordinate
@@ -69,16 +71,19 @@
 //! forwarded to us by someone else. And in this case, we aren't measuring the actual RTT. Instead,
 //! we're using the NCs to estimate RTT.
 //!
+//! This example also uses the type alias [`NetworkCoordinate3D`] instead of its equivalent
+//! [`NetworkCoordinate<3>`].
+//!
 //! ```
-//! use vivaldi_nc::NetworkCoordinate;
+//! use vivaldi_nc::NetworkCoordinate3D;
 //!
 //! // create our local NC as a 3-dimensional Vivaldi coordinate
-//! let mut my_nc = NetworkCoordinate::<3>::new();
+//! let mut my_nc = NetworkCoordinate3D::new();
 //!
 //! // mock up a remote NC for the sake of this example (normally the node would actually receive
 //! // this from a remote node)
-//! let received_msg = "{\"position\":[{\"inner\":[1.5,0.5,2.0]},0.1],\"error\":1.0}";
+//! let received_msg = "{\"position\":[1.5,0.5,2.0],\"height\":0.1,\"error\":1.0}";
-//! let remote_nc: NetworkCoordinate<3> = serde_json::from_str(received_msg).unwrap();
+//! let remote_nc: NetworkCoordinate3D = serde_json::from_str(received_msg).unwrap();
 //!
 //! // estimate the RTT to this remote node without measuring it directly
 //! let rtt_estimated = my_nc.estimated_rtt(&remote_nc);
@@ -91,6 +96,12 @@
 mod height_vector;
 mod vector;
 
+// make sure we don't have conflicting features
+#[cfg(all(feature = "f32", feature = "f64"))]
+compile_error!("feature \"f32\" and feature \"f64\" cannot be enabled at the same time");
+
 // publish our interface
 pub mod network_coordinate;
 pub use network_coordinate::NetworkCoordinate;
+pub use network_coordinate::NetworkCoordinate2D;
+pub use network_coordinate::NetworkCoordinate3D;

src/network_coordinate.rs

@@ -31,19 +31,28 @@ use serde::{Deserialize, Serialize};
 
 use crate::height_vector::HeightVector;
 
+//
+// **** Features ****
+//
+#[cfg(feature = "f32")]
+type FloatType = f32;
+
+#[cfg(feature = "f64")]
+type FloatType = f64;
+
 //
 // **** Constants ****
 //
 
 // Vivaldi tuning parameters
-const C_ERROR: f32 = 0.25;
+const C_ERROR: FloatType = 0.25;
-const C_DELTA: f32 = 0.25;
+const C_DELTA: FloatType = 0.25;
 
 // initial error value
-const DEFAULT_ERROR: f32 = 200.0;
+const DEFAULT_ERROR: FloatType = 200.0;
 
 // error should always be greater than zero
-const MIN_ERROR: f32 = f32::EPSILON;
+const MIN_ERROR: FloatType = FloatType::EPSILON;
 
 //
 // **** Structs ****
@@ -51,10 +60,25 @@ const MIN_ERROR: f32 = f32::EPSILON;
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct NetworkCoordinate<const N: usize> {
-    position: HeightVector<N>,
+    #[serde(flatten)]
-    error: f32,
+    heightvec: HeightVector<N>,
+    error: FloatType,
 }
 
+// type aliases for convenience
+
+/// A 2D [`NetworkCoordinate`]. Includes a 2D Euclidean position and a height.
+///
+/// This type alias is just for convenience. It's functionally equivalent to
+/// `NetworkCoordinate<2>`.
+pub type NetworkCoordinate2D = NetworkCoordinate<2>;
+
+/// A 3D [`NetworkCoordinate`]. Includes a 3D Euclidean position and a height.
+///
+/// This type alias is just for convenience. It's functionally equivalent to
+/// `NetworkCoordinate<3>`.
+pub type NetworkCoordinate3D = NetworkCoordinate<3>;
+
 //
 // **** Implementations ****
 //
@@ -106,7 +130,11 @@ impl<const N: usize> NetworkCoordinate<N> {
     ///
     pub fn estimated_rtt(&self, rhs: &Self) -> Duration {
         // estimated rss is euclidean distance between the two plus the sum of the heights
-        Duration::from_secs_f32((self.position - rhs.position).len() / 1000.0)
+        #[cfg(feature = "f32")]
+        return Duration::from_secs_f32((self.heightvec - rhs.heightvec).len() / 1000.0);
+
+        #[cfg(feature = "f64")]
+        return Duration::from_secs_f64((self.heightvec - rhs.heightvec).len() / 1000.0);
     }
 
     /// Given another Vivaldi [`NetworkCoordinate`], adjust our coordinateto better represent the actual round
@@ -140,15 +168,22 @@ impl<const N: usize> NetworkCoordinate<N> {
     /// local.update(&remote, rtt);
     /// ```
     pub fn update(&mut self, rhs: &Self, rtt: Duration) -> &Self {
+        // convert Durations into FloatType as fractional milliseconds for convenience
+        #[cfg(feature = "f32")]
+        let rtt_ms = rtt.as_secs_f32() * 1000.0;
+        #[cfg(feature = "f32")]
+        let rtt_estimated_ms = self.estimated_rtt(rhs).as_secs_f32() * 1000.0;
+
+        #[cfg(feature = "f64")]
+        let rtt_ms = rtt.as_secs_f64() * 1000.0;
+        #[cfg(feature = "f64")]
+        let rtt_estimated_ms = self.estimated_rtt(rhs).as_secs_f64() * 1000.0;
+
         // rtt needs to be positive
-        if rtt.as_secs_f32() < 0.0 {
+        if rtt_ms < 0.0 {
             return self;
         }
 
-        // convert Durations into f32s as fractional milliseconds for convenience
-        let rtt_ms = rtt.as_secs_f32() * 1000.0;
-        let rtt_estimated_ms = self.estimated_rtt(rhs).as_secs_f32() * 1000.0;
-
         // Sample weight balances local and remote error. (1)
         // w = ei /(ei + ej )
         let w = self.error / (self.error + rhs.error);
@@ -166,11 +201,12 @@ impl<const N: usize> NetworkCoordinate<N> {
         // δ = cc × w
         let delta = C_DELTA * w;
         // xi = xi + δ × (rtt − ‖xi − xj ‖) × u(xi − xj)
-        self.position = self.position + (self.position - rhs.position).normalized() * delta * error;
+        self.heightvec =
+            self.heightvec + (self.heightvec - rhs.heightvec).normalized() * delta * error;
 
         // if we ended up with an invalid coordinate, return a new random coordinate with default
         // error
-        if self.position.is_invalid() {
+        if self.heightvec.is_invalid() {
             *self = Self::new()
         }
 
@@ -180,7 +216,7 @@ impl<const N: usize> NetworkCoordinate<N> {
 
     /// getter for error value - useful for consumers to understand the estimated accuracty of this
     /// `NetworkCoordinate`
-    pub fn error(&self) -> f32 {
+    pub fn error(&self) -> FloatType {
         self.error
     }
 }
@@ -193,7 +229,7 @@ impl<const N: usize> Default for NetworkCoordinate<N> {
     /// A default `NetworkCoordinate` has a random position and DEFAULT_ERROR
     fn default() -> Self {
         Self {
-            position: HeightVector::<N>::random(),
+            heightvec: HeightVector::<N>::random(),
             error: DEFAULT_ERROR,
         }
     }
@@ -258,8 +294,8 @@ mod tests {
 
         // verify the initial error
         let error =
-        (slc.error.powf(2.0) + nyc.error.powf(2.0) + lax.error.powf(2.0) + mad.error.powf(2.0))
+            (slc.error.powf(2.0) + nyc.error.powf(2.0) + lax.error.powf(2.0) + mad.error.powf(2.0))
-            .sqrt();
+                .sqrt();
         assert_eq!(error, 400.0);
 
         // iterate plenty of times to converge and minimize error
@@ -292,11 +328,11 @@ mod tests {
     #[test]
     fn test_serde() {
         // start with JSON, deserialize it
-        let s = "{\"position\":[{\"inner\":[1.5,0.5,2.0]},0.1],\"error\":1.0}";
+        let s = "{\"position\":[1.5,0.5,2.0],\"height\":0.1,\"error\":1.0}";
         let a: NetworkCoordinate<3> = serde_json::from_str(s).unwrap();
 
         // make sure it's the right length and works like we expect a normal NC
-        assert_approx_eq!(a.position.len(), 2.649_509, 0.001);
+        assert_approx_eq!(a.heightvec.len(), 2.649_509, 0.001);
         assert_eq!(a.error, 1.0);
         assert_eq!(a.estimated_rtt(&a).as_millis(), 0);
 
@@ -308,9 +344,9 @@ mod tests {
     #[test]
     fn test_estimated_rtt() {
         // start with JSON, deserialize it
-        let s = "{\"position\":[{\"inner\":[1.5,0.5,2.0]},25.0],\"error\":1.0}";
+        let s = "{\"position\":[1.5,0.5,2.0],\"height\":25.0,\"error\":1.0}";
         let a: NetworkCoordinate<3> = serde_json::from_str(s).unwrap();
-        let s = "{\"position\":[{\"inner\":[-1.5,-0.5,-2.0]},50.0],\"error\":1.0}";
+        let s = "{\"position\":[-1.5,-0.5,-2.0],\"height\":50.0,\"error\":1.0}";
         let b: NetworkCoordinate<3> = serde_json::from_str(s).unwrap();
 
         let estimate = a.estimated_rtt(&b);

src/vector.rs

@@ -24,6 +24,7 @@ pub(crate) struct Vector<T, const N: usize>
 where
     T: Float + Serialize + for<'d> Deserialize<'d>,
 {
+    #[serde(rename = "position")]
     #[serde_as(as = "[_; N]")]
     inner: [T; N],
 }
@@ -279,7 +280,7 @@ mod tests {
     fn test_serde() {
         let a = Vector::<f32, 3>::from([1.0, 2.0, 3.0]);
         let s = serde_json::to_string(&a);
-        assert_eq!(s.as_ref().unwrap(), "{\"inner\":[1.0,2.0,3.0]}");
+        assert_eq!(s.as_ref().unwrap(), "{\"position\":[1.0,2.0,3.0]}");
         assert!(s.is_ok());
     }
 }