v2.1.0: Round-to-nearest accuracy fixes and release automation

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.88
+      - uses: dtolnay/rust-toolchain@1.95
       - uses: Swatinem/rust-cache@v2
       - run: cargo check --features std
 

.github/workflows/publish.yml

@@ -1,17 +1,60 @@
 name: Publish
 
+# Releases on merge to main: when Cargo.toml's version is not yet on
+# crates.io, this workflow tests, tags, publishes, and creates the
+# GitHub release in a single run.
+#
+# Everything happens in one workflow because tag pushes made with the
+# default GITHUB_TOKEN deliberately do not trigger other workflows —
+# that is what broke the old auto-tag.yml → publish.yml chain. Here the
+# tag is an output of the run, not a trigger, so no PAT is needed.
+#
+# Every step is idempotent: an already-published version short-circuits
+# the run, and an existing tag is left in place. A failed run can be
+# retried from the Actions tab (or `gh workflow run publish.yml`).
+
 on:
   push:
-    tags:
-      - 'v*.*.*'
+    branches: [main]
+  workflow_dispatch:
 
 env:
   CARGO_TERM_COLOR: always
 
+concurrency:
+  group: publish
+  cancel-in-progress: false
+
 jobs:
-  # Run full test suite before publishing
+  check:
+    name: Check release needed
+    runs-on: ubuntu-latest
+    outputs:
+      version: ${{ steps.check.outputs.version }}
+      release: ${{ steps.check.outputs.release }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Compare Cargo.toml version against crates.io
+        id: check
+        run: |
+          VERSION=$(cargo metadata --no-deps --format-version 1 | jq -r '.packages[0].version')
+          echo "version=$VERSION" >> "$GITHUB_OUTPUT"
+          # The sparse index needs no auth and serves one JSON line per
+          # published version. A 404 means the crate has never been
+          # published, which also means "release".
+          if curl -sf "https://index.crates.io/fi/xe/fixed_analytics" \
+              | jq -e --arg v "$VERSION" 'select(.vers == $v)' > /dev/null; then
+            echo "release=false" >> "$GITHUB_OUTPUT"
+            echo "v$VERSION is already on crates.io — nothing to release"
+          else
+            echo "release=true" >> "$GITHUB_OUTPUT"
+            echo "v$VERSION is not on crates.io — releasing"
+          fi
+
   test:
     name: Pre-publish Tests
+    needs: check
+    if: needs.check.outputs.release == 'true'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -23,53 +66,54 @@ jobs:
         env:
           RUSTDOCFLAGS: -Dwarnings
 
-  # Publish to crates.io
-  publish:
-    name: Publish to crates.io
-    needs: test
+  release:
+    name: Tag, publish, and release
+    needs: [check, test]
+    if: needs.check.outputs.release == 'true'
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    env:
+      VERSION: ${{ needs.check.outputs.version }}
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2
-
-      - name: Verify version matches tag
+
+      # Tag before publishing: a tag without a crates.io release heals
+      # on retry (the tag step skips, publish runs); the reverse order
+      # would leave an already-published version that the check job
+      # filters out, so the tag would never be created.
+      - name: Create tag if missing
         run: |
-          CARGO_VERSION=$(cargo metadata --no-deps --format-version 1 | jq -r '.packages[0].version')
-          TAG_VERSION=${GITHUB_REF#refs/tags/v}
-          if [ "$CARGO_VERSION" != "$TAG_VERSION" ]; then
-            echo "Version mismatch: Cargo.toml has $CARGO_VERSION but tag is $TAG_VERSION"
-            exit 1
+          if git ls-remote --tags origin "refs/tags/v$VERSION" | grep -q .; then
+            echo "Tag v$VERSION already exists, keeping it"
+          else
+            git tag "v$VERSION"
+            git push origin "v$VERSION"
           fi
-      
-      - name: Publish
+
+      - name: Publish to crates.io
         run: cargo publish
         env:
           CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
 
-  # Create GitHub release with auto-generated notes
-  release:
-    name: Create GitHub Release
-    needs: publish
-    runs-on: ubuntu-latest
-    permissions:
-      contents: write
-    steps:
-      - uses: actions/checkout@v4
-      - uses: softprops/action-gh-release@v1
+      - name: Create GitHub release
+        uses: softprops/action-gh-release@v1
         with:
+          tag_name: v${{ needs.check.outputs.version }}
           generate_release_notes: true
           body: |
             ## Installation
-            
+
             ```toml
             [dependencies]
-            fixed_analytics = "${{ github.ref_name }}"
+            fixed_analytics = "${{ needs.check.outputs.version }}"
             ```
-            
+
             For `no_std` environments:
-            
+
             ```toml
             [dependencies]
-            fixed_analytics = { version = "${{ github.ref_name }}", default-features = false }
-            ```
+            fixed_analytics = { version = "${{ needs.check.outputs.version }}", default-features = false }
+            ```

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "fixed_analytics"
-version = "2.0.1"
+version = "2.1.0"
 edition = "2024"
-rust-version = "1.88"
+rust-version = "1.95"
 authors = ["David Gathercole"]
 description = "Fixed-point mathematical functions. Accurate, deterministic, and panic free."
 repository = "https://github.com/GeEom/fixed_analytics"
@@ -22,7 +22,7 @@ std = []
 verify-no-panic = ["dep:no-panic"]
 
 [dependencies]
-fixed = "1.30"
+fixed = "1.31"
 no-panic = { version = "0.1", optional = true }
 
 [dev-dependencies]

README.md

@@ -26,11 +26,11 @@ assert!((log.to_num::<f32>() - 1.0).abs() < 0.01);
 
 ## Installation
 
-Requires Rust 1.88 or later.
+Requires Rust 1.95 or later.
 
 ```toml
 [dependencies]
-fixed_analytics = "2.0.1"
+fixed_analytics = "2.1.0"
 ```
 
 For `no_std` environments:
@@ -82,9 +82,9 @@ Relative error statistics measured against MPFR reference implementations. Accur
 | sin | 6.06e-4 | 8.78e-5 | 1.28e-3 | 1.16e-8 | 1.68e-9 | 2.43e-8 |
 | cos | 6.45e-4 | 9.03e-5 | 1.38e-3 | 1.22e-8 | 1.72e-9 | 2.64e-8 |
 | tan | 7.20e-5 | 3.57e-5 | 2.20e-4 | 1.28e-9 | 3.98e-10 | 3.03e-9 |
-| asin | 2.87e-4 | 5.93e-5 | 6.46e-4 | 5.34e-9 | 8.82e-10 | 1.03e-8 |
-| acos | 3.61e-5 | 2.18e-5 | 1.14e-4 | 5.37e-10 | 3.19e-10 | 1.71e-9 |
-| atan | 2.71e-5 | 2.21e-5 | 6.29e-5 | 3.69e-10 | 2.92e-10 | 8.74e-10 |
+| asin | 1.85e-4 | 3.60e-5 | 4.75e-4 | 4.49e-9 | 7.35e-10 | 8.89e-9 |
+| acos | 2.33e-5 | 1.47e-5 | 6.86e-5 | 4.51e-10 | 2.71e-10 | 1.38e-9 |
+| atan | 1.50e-5 | 1.23e-5 | 3.45e-5 | 3.01e-10 | 2.44e-10 | 7.05e-10 |
 | sinh | 9.80e-5 | 6.23e-5 | 2.79e-4 | 1.52e-9 | 9.64e-10 | 4.29e-9 |
 | cosh | 9.40e-5 | 5.75e-5 | 2.77e-4 | 1.44e-9 | 8.90e-10 | 4.25e-9 |
 | tanh | 1.60e-5 | 1.32e-5 | 2.56e-5 | 2.25e-10 | 1.22e-10 | 3.90e-10 |
@@ -93,10 +93,10 @@ Relative error statistics measured against MPFR reference implementations. Accur
 | acosh | 6.74e-4 | 5.21e-4 | 1.80e-3 | 1.05e-8 | 7.96e-9 | 2.88e-8 |
 | atanh | 3.01e-4 | 5.90e-5 | 6.25e-4 | 6.68e-9 | 1.32e-9 | 1.44e-8 |
 | acoth | 2.10e-3 | 1.33e-3 | 6.67e-3 | 4.26e-8 | 2.62e-8 | 1.39e-7 |
-| exp | 1.14e-2 | 2.32e-5 | 7.88e-2 | 1.91e-7 | 1.73e-9 | 1.30e-6 |
+| exp | 5.98e-3 | 1.47e-5 | 4.13e-2 | 9.49e-8 | 1.50e-9 | 6.50e-7 |
 | ln | 1.35e-5 | 8.76e-6 | 2.97e-5 | 4.50e-10 | 3.48e-10 | 9.17e-10 |
 | log2 | 1.33e-5 | 8.48e-6 | 2.92e-5 | 3.46e-10 | 2.24e-10 | 7.21e-10 |
 | log10 | 1.44e-5 | 9.28e-6 | 3.14e-5 | 4.49e-10 | 3.27e-10 | 9.07e-10 |
-| pow2 | 7.21e-4 | 2.58e-5 | 4.72e-3 | 1.13e-8 | 4.93e-10 | 7.43e-8 |
+| pow2 | 3.62e-4 | 2.24e-5 | 2.37e-3 | 5.64e-9 | 4.29e-10 | 3.67e-8 |
 | sqrt | 1.77e-7 | 1.16e-7 | 4.74e-7 | 2.70e-12 | 1.78e-12 | 7.16e-12 |
 <!-- ACCURACY_END -->

codecov.yml

@@ -4,16 +4,16 @@ codecov:
 coverage:
   precision: 2
   round: down
-  range: "70...100"
+  range: "90...100"
 
   status:
     project:
       default:
-        target: 80%
+        target: 95%
         threshold: 1%
     patch:
       default:
-        target: 80%
+        target: 85%
 
 comment:
   layout: "reach,diff,flags,files,footer"

src/kernel/cordic.rs

@@ -41,6 +41,36 @@ const fn table_lookup(table: &[i64; 64], index: u32) -> i64 {
     table[index as usize]
 }
 
+/// Converts an I1F63 table constant to `T`, rounding to nearest.
+///
+/// `CordicNumber::from_i1f63` truncates, which biases every converted
+/// angle low by up to one ulp. For circular CORDIC the accumulated z is
+/// dominated by this table quantization, so rounding to nearest halves
+/// the worst case and removes the systematic bias.
+///
+/// Hyperbolic CORDIC deliberately keeps the truncating conversion: its
+/// datapath shifts carry their own bias, which the truncated table
+/// angles partially cancel (measured, not designed — see the accuracy
+/// baseline history).
+fn from_i1f63_rounded<T: CordicNumber>(bits: i64) -> T {
+    let truncated = T::from_i1f63(bits);
+    let frac = T::frac_bits();
+    if frac >= 63 {
+        // Conversion is exact; nothing to round.
+        return truncated;
+    }
+    // The conversion discards the low (63 - frac) bits. If the highest
+    // discarded bit is set, the true value is at least half an output
+    // ulp above the truncated result, so round up by one ulp.
+    let shift = 63 - frac;
+    if (bits >> (shift - 1)) & 1 == 1 {
+        let ulp = T::one() >> frac;
+        truncated.saturating_add(ulp)
+    } else {
+        truncated
+    }
+}
+
 /// Performs circular CORDIC in vectoring mode.
 ///
 /// Given an initial vector (x, y), rotates it until y ≈ 0.
@@ -68,7 +98,7 @@ pub fn circular_vectoring<T: CordicNumber>(mut x: T, mut y: T, mut z: T) -> (T,
     let iterations = T::frac_bits().min(62);
 
     for i in 0..iterations {
-        let angle = T::from_i1f63(table_lookup(&ATAN_TABLE, i));
+        let angle = from_i1f63_rounded::<T>(table_lookup(&ATAN_TABLE, i));
 
         if y < zero {
             // y is negative, rotate counter-clockwise to bring y toward zero