Generalise to GTMD Distributions

.github/actions/cache-data/action.yml

@@ -10,7 +10,7 @@ runs:
       uses: actions/cache@v4
       with:
         path: neopdf-data
-        key: data-v11
+        key: data-v12
     - name: Download data if cache miss
       if: steps.cache-data.outputs.cache-hit != 'true'
       run: |

.github/workflows/benchmarks.yml

@@ -34,7 +34,7 @@ jobs:
         id: bench
         run: |
           export NEOPDF_DATA_PATH=${PWD}/neopdf-data
-          # The awk command filters out the verbose test summary before the benchmark results.
+          # TODO: remove the version specification
           cargo bench -p neopdf -- --nocapture | awk '/^test result: ok\./ {p=1; next} p' | tee benchmark_results.txt
 
       - name: Post benchmark results as a PR comment

.github/workflows/run-python.yml

@@ -9,7 +9,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
 
     steps:
       - uses: actions/checkout@v4

.github/workflows/run-rust.yml

@@ -12,8 +12,9 @@ env:
 jobs:
   build:
     strategy:
+      fail-fast: false
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -37,9 +38,12 @@ jobs:
         run: |
           export NEOPDF_DATA_PATH=${PWD}/neopdf-data
           cargo test --workspace --exclude neopdf_pyapi --exclude neopdf_tmdlib --exclude neopdf_wolfram --no-fail-fast 2> >(tee stderr 1>&2)
-          sed -i 's/\x1B\[[0-9;]\{1,\}[A-Za-z]//g' stderr
+          if [ "${{ matrix.os }}" != "macos-latest" ]; then
+            sed -i 's/\x1B\[[0-9;]\{1,\}[A-Za-z]//g' stderr
+          fi
 
       - name: Generate code coverage
+        if: matrix.os == 'ubuntu-latest'
         run: |
           find . -name '*.profraw' -exec $(rustc --print target-libdir)/../bin/llvm-profdata merge -sparse -o neopdf.profdata {} +
           ( sed -nE 's/[[:space:]]+Running( unittests|) [^[:space:]]+ \(([^)]+)\)/\2/p' stderr && echo target/debug/doctestbins/*/rust_out | tr ' ' "\n" ) | \
@@ -57,6 +61,7 @@ jobs:
           grep SF lcov.info | sort -u | sed 's/SF://'
 
       - name: Upload to codecov.io
+        if: matrix.os == 'ubuntu-latest'
         uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}

CHANGELOG.md

@@ -7,6 +7,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Added `LogFourCubic` and `LogFiveCubic` interpolation strategies.
+- Added new methods to the Fortran and C/C++ APIs to write and compress grids
+  with `xi` and `delta` dependence.
+
+### Changed
+
+- Breaking change to the Python API for the `PyMetaData` and `PySubgrid`.
+- Bump `PyO3` and `numpy` versions to `v0.27` to support Python `3.14`.
+- Extended the Grid layout to support GTMDs and GPDs (https://github.com/QCDLab/neopdf/pull/79).
+
 ## [0.2.0] - 06/10/2025
 
 ### Added

Cargo.toml

@@ -36,8 +36,8 @@ clap = { version = "4.5", features = ["derive"] }
 terminal_size = "0.3.0"
 
 # Python bindings
-numpy = "0.25"
-pyo3 = { version = "0.25", features = ["extension-module"] }
+numpy = "0.27"
+pyo3 = { version = "0.27", features = ["extension-module"] }
 
 # Build dependencies
 cbindgen = "0.26.0"

README.md

@@ -30,14 +30,13 @@
 </div>
 
 <p align="justify">
-  <b>NeoPDF</b> is a fast, reliable, and scalable interpolation library for both <b>collinear</b>
-  and <b>transverse momentum dependent</b> Parton Distribution Functions with <b>modern features</b>
-  designed for both present and future hadron collider experiments:
+  <b>NeoPDF</b> is a fast, reliable, and scalable interpolation library for <b>Non-Perturbative Distribution Functions</b>
+  with <b>modern features</b> designed for both present and future hadron collider experiments:
 
   <ul>
     <li>
     <p align="justify">
-      Beyond interpolations over the kinematic variables (<b>x</b>, <b>kT</b>, <b>Q2</b>), NeoPDF
+      Beyond interpolations over the kinematic variables (<b>x</b>, <b>ξ</b>, <b>Δ</b>, <b>kT</b>, <b>Q²</b>), NeoPDF
       also supports interpolations along the nucleon numbers <b>A</b> (relevant for <b>nuclear</b> PDFs
       and TMDs) and the strong coupling <b>αs(MZ)</b>.
     </p>
@@ -60,6 +59,30 @@
   </ul>
 </p>
 
+## Supported distributions
+
+<p align="justify">
+  NeoPDF supports generic classes of distributions that are functions of different combinations of the kinematic
+  variables. Examples of distribution functions are given in the diagram below with their simplified relationships.
+</p>
+
+```mermaid
+graph TD
+
+A["**Generalized Tranverse Momentum Distribution** <br> GTMD(x, ξ, Δ, kT​​, Q²)"]
+
+A -->|∫ dkT| B["**Generalized Parton Distributions** <br> GPD(x, ξ, Δ, Q²)"]
+A -->|ξ → 0, Δ → 0| C["**Transverse Momentum Distributions** <br> TMD(x, kT, Q²)"]
+
+B -->|ξ → 0, Δ → 0| D["**Collinear Parton Distribution Functions** <br> PDF(x, Q²)"]
+C -->|∫ dkT| D
+
+style A fill:#ffd580,stroke:#b8860b,stroke-width:2px
+style B fill:#add8e6,stroke:#1e90ff,stroke-width:2px
+style C fill:#98fb98,stroke:#228b22,stroke-width:2px
+style D fill:#f08080,stroke:#8b0000,stroke-width:2px
+```
+
 ## Quick Links
 
 - [Documentation](https://qcdlab.github.io/neopdf/) | [Rust Crate Documentation](https://docs.rs/neopdf/0.1.1/neopdf/) | [C++ API Reference](https://neopdf.readthedocs.io/en/latest/)

neopdf/Cargo.toml

@@ -30,6 +30,9 @@ regex.workspace = true
 git-version.workspace = true
 indicatif.workspace = true
 
+# For backward compatibility with v0.2.0 format
+neopdf_legacy = { package = "neopdf", version = "0.2.0" }
+
 [dev-dependencies]
 criterion.workspace = true
 

neopdf/src/alphas.rs

@@ -82,12 +82,14 @@ impl AlphaSAnalytic {
             meta.alphas_order_qcd
         };
 
+        let (_m_up, _m_down, _m_strange, m_charm, m_bottom, m_top) = meta.quark_masses();
+
         Ok(Self {
             qcd_order: alphas_order_qcd,
             lambda_maps,
-            mc_sq: meta.m_charm * meta.m_charm,
-            mb_sq: meta.m_bottom * meta.m_bottom,
-            mt_sq: meta.m_top * meta.m_top,
+            mc_sq: m_charm * m_charm,
+            mb_sq: m_bottom * m_bottom,
+            mt_sq: m_top * m_top,
             num_fl: meta.number_flavors,
             fl_scheme: meta.flavor_scheme.clone(),
         })
@@ -162,7 +164,7 @@ impl AlphaSAnalytic {
         let mut tmp = 1.0;
 
         if self.qcd_order == 0 {
-            return 0.118; // _alpha_mz reference value
+            return 0.118; // `_alpha_mz` reference value
         }
 
         if self.qcd_order > 1 {
@@ -202,20 +204,22 @@ pub struct AlphaSInterpol {
 
 impl AlphaSInterpol {
     pub fn from_metadata(meta: &MetaData) -> Result<Self, String> {
-        let (q_values, alphas_vals): (Vec<_>, Vec<_>) = meta
-            .alphas_q_values
+        let alphas_q_values = &meta.alphas_q_values;
+        let alphas_vals = &meta.alphas_vals;
+
+        let (q_values, alphas_vals_filtered): (Vec<_>, Vec<_>) = alphas_q_values
             .iter()
-            .zip(&meta.alphas_vals)
+            .zip(alphas_vals)
             .enumerate()
-            .filter(|(i, (&q, _))| *i == 0 || q != meta.alphas_q_values[i - 1])
+            .filter(|(i, (&q, _))| *i == 0 || q != alphas_q_values[i - 1])
             .map(|(_, (&q, &alpha))| (q, alpha))
             .unzip();
 
         let q2_values: Vec<f64> = q_values.iter().map(|&q| (q * q).ln()).collect();
 
         let interpolator = Interp1D::new(
             q2_values.into(),
-            alphas_vals.into(),
+            alphas_vals_filtered.into(),
             AlphaSCubicInterpolation,
             Extrapolate::Error,
         )