add support for clarabel (#48)

* add support for clarabel

closes #27

* test clarabel

* fmt

.github/workflows/rust.yml

@@ -9,9 +9,6 @@ on:
 
 env:
   CARGO_TERM_COLOR: always
-  # 'lpsolve' and 'cplex-rs' features are incompatible
-  ALL_FEATURES_EXCEPT_CPLEX: "scip,singlethread-cbc,coin_cbc,highs,lp-solvers,minilp,russcip,lpsolve"
-  ALL_FEATURES_EXCEPT_LPSOLVE: "scip,singlethread-cbc,coin_cbc,highs,lp-solvers,minilp,russcip,cplex-rs"
 
 jobs:
   build:
@@ -41,16 +38,11 @@ jobs:
           curl -LO https://github.com/rust-or/good_lp/releases/download/cplex/cplex.bin
           chmod u+x cplex.bin
           ./cplex.bin -f ./.github/cplex/response.properties
-      - name: Build with all features except cplex-rs
-        run: cargo build --features ${{ env.ALL_FEATURES_EXCEPT_CPLEX }} --tests
-      - name: Run tests with all features except cplex-rs
+      - name: Build with all default solvers (no cplex)
+        run: cargo build --features all_default_solvers --tests
+      - name: Run tests with all default solvers (no cplex)
         # test on a single thread. See: https://github.com/KardinalAI/coin_cbc/issues/9
-        run: cargo test  --features ${{ env.ALL_FEATURES_EXCEPT_CPLEX }} -- --test-threads=1
-      - name: Build with all features except lpsolve
-        run: cargo build --features ${{ env.ALL_FEATURES_EXCEPT_LPSOLVE }} --tests
-      - name: Run tests with all features except lpsolve
-        # test on a single thread. See: https://github.com/KardinalAI/coin_cbc/issues/9
-        run: cargo test  --features ${{ env.ALL_FEATURES_EXCEPT_LPSOLVE }} -- --test-threads=1
+        run: cargo test  --features all_default_solvers -- --test-threads=1
       - name: Run tests with minilp
         run: cargo test --no-default-features --features minilp
       - name: Run tests with lpsolve
@@ -63,4 +55,6 @@ jobs:
         run: cargo test --no-default-features --features scip
       - name: Run tests with CPLEX
         run: cargo test --no-default-features --features cplex-rs
+      - name: Run tests with Clarabel
+        run: cargo test --no-default-features --features clarabel
       - run: cargo bench

.vscode/settings.json

@@ -0,0 +1,8 @@
+{
+    "rust-analyzer.linkedProjects": [
+        "./Cargo.toml",
+    ],
+    "rust-analyzer.cargo.features": [
+        "all_default_solvers"
+    ]
+}

CONTRIBUTING.md

@@ -17,4 +17,5 @@ Adding a new solver should not take more than a few hundred lines of code, tests
        You can generally reuse data structures provided by the library for which you are creating a wrapper. 
     - implement a function named after your solver that takes an [`UnsolvedProblem`](https://docs.rs/good_lp/latest/good_lp/variable/struct.UnsolvedProblem.html) and returns the struct you defined above.
     - implement the [`SolverModel`](https://docs.rs/good_lp/latest/good_lp/index.html#reexport.SolverModel) trait for your new problem type.
+    - add your solver to `lib.rs` and to the `all_default_solvers` feature in Cargo.toml. 
     - open a [pull request](https://github.com/rust-or/good_lp/pulls)

Cargo.toml

@@ -15,6 +15,7 @@ categories = ["mathematics", "algorithms", "science", "api-bindings", "data-stru
 default = ["coin_cbc", "singlethread-cbc"]
 singlethread-cbc = ["coin_cbc?/singlethread-cbc"]
 scip = ["russcip"]
+all_default_solvers = ["coin_cbc", "minilp", "lpsolve", "highs", "russcip", "lp-solvers", "clarabel"] # cplex-rs is not included because it is incompatible with lpsolve
 
 [dependencies]
 coin_cbc = { version = "0.1", optional = true, default-features = false }
@@ -24,6 +25,7 @@ highs = { version = "1.5.0", optional = true }
 russcip = { version = "0.3.4", optional = true }
 lp-solvers = { version = "1.0.0", features = ["cplex"], optional = true }
 cplex-rs = { version = "0.1", optional = true }
+clarabel = { version = "0.7.1", optional = true, features=[] }
 fnv = "1.0.5"
 
 [dev-dependencies]
@@ -36,7 +38,8 @@ harness = false
 
 [package.metadata.docs.rs]
 # Display the documentation for all solvers on docs.rs
-all-features = true
+all-features = false
+features = [ "all_default_solvers" ]
 default-target = "x86_64-unknown-linux-gnu"
 targets = ["x86_64-unknown-linux-gnu"]
 rustdoc-args = ["--cfg", "docsrs"]

README.md

@@ -76,6 +76,7 @@ you can also activate other solvers using cargo features.
 | [`lp-solvers`][lps]    | ✅                | ✅              | ✅                     | ❌   |
 | [`scip`][scip]         | ✅                | ✅              | ❌                     | ✅   |
 | [`cplex-rs`][cplex]    | ✅                | ❌              | ✅\+\+                 | ✅   |
+| [`clarabel`][clarabel] | ❌                | ✅              | ✅                     | ✅   |
 
 - \* no C compiler: builds with only cargo, without requiring you to install a C compiler
 - \*\* no additional libs: works without additional libraries at runtime, all the dependencies are statically linked
@@ -190,6 +191,13 @@ Since cplex-rs-sys uses [bindgen](https://github.com/rust-lang/rust-bindgen) to
 
 [cplex]: https://www.ibm.com/products/ilog-cplex-optimization-studio/cplex-optimizer
 
+### [clarabel][clarabel]
+
+[Clarabel](https://github.com/oxfordcontrol/Clarabel.rs) is a free 
+([Apache 2.0](https://github.com/oxfordcontrol/Clarabel.rs/blob/main/LICENSE.md))
+linear programming solver written in Rust by the
+[Oxford Control group](https://eng.ox.ac.uk/control/).
+
 ## Variable types
 
 `good_lp` internally represents all [variable](https://docs.rs/good_lp/1.4.0/good_lp/variable/struct.Variable.html) values and coefficients as `f64`.

src/affine_expression_trait.rs

@@ -49,7 +49,7 @@ pub trait IntoAffineExpression {
     /// ```
     ///
     /// ### Evaluate an expression with a HashMap
-    /// A [HashMap] is a valid [Solution]
+    /// A [std::collections::HashMap] is a valid [Solution]
     ///
     /// ```rust
     /// use std::collections::HashMap;

src/constraint.rs

@@ -102,9 +102,7 @@ impl_shifts!(Expression Variable);
 /// ## Full example
 ///
 /// ```
-/// # fn assert_float_eq(a:f64, b:f64) {
-/// #   assert!((a-b).abs() <= 16. * f64::EPSILON, "{} != {}", a, b);
-/// # }
+/// # use float_eq::assert_float_eq;
 /// use good_lp::*;
 ///
 /// let mut vars = variables!();
@@ -116,8 +114,8 @@ impl_shifts!(Expression Variable);
 ///     .with(constraint!(a - 5 <= b / 2))
 ///     .with(constraint!(b == a))
 ///     .solve().unwrap();
-/// assert_float_eq(10., solution.value(a));
-/// assert_float_eq(10., solution.value(b));
+/// assert_float_eq!(10., solution.value(a), abs<=1e-8);
+/// assert_float_eq!(10., solution.value(b), abs<=1e-8);
 /// ```
 #[macro_export]
 macro_rules! constraint {

src/lib.rs

@@ -21,8 +21,9 @@
 //!      .with(1 + a >> 4. - b)
 //!      .solve()?;
 //!
-//!  assert_eq!(solution.value(a), 1.);
-//!  assert_eq!(solution.value(b), 3.);
+//! # use float_eq::assert_float_eq;
+//!  assert_float_eq!(solution.value(a), 1., abs <= 1e-8);
+//!  assert_float_eq!(solution.value(b), 3., abs <= 1e-8);
 //!  # Ok::<_, good_lp::ResolutionError>(())
 //!  ```
 //!
@@ -68,6 +69,18 @@ pub use affine_expression_trait::IntoAffineExpression;
 pub use cardinality_constraint_solver_trait::CardinalityConstraintSolver;
 pub use constraint::Constraint;
 pub use expression::Expression;
+#[cfg(not(any(
+    feature = "coin_cbc",
+    feature = "minilp",
+    feature = "lpsolve",
+    feature = "highs",
+    feature = "scip",
+    feature = "cplex-rs",
+)))]
+#[cfg(feature = "clarabel")]
+pub use solvers::clarabel::clarabel as default_solver;
+#[cfg(feature = "clarabel")]
+pub use solvers::clarabel::clarabel;
 #[cfg_attr(docsrs, doc(cfg(feature = "coin_cbc")))]
 #[cfg(feature = "coin_cbc")]
 pub use solvers::coin_cbc::coin_cbc;
@@ -146,6 +159,7 @@ pub const default_solver: LpSolver<
     feature = "lp-solvers",
     feature = "scip",
     feature = "cplex-rs",
+    feature = "clarabel",
 )))]
 compile_error!(
     "No solver available. \
@@ -162,7 +176,7 @@ good_lp = { version = \"*\", features = [\"minilp\"] }
 #[cfg(all(feature = "lpsolve", feature = "cplex-rs",))]
 compile_error!(
     "'lpsolve' and 'cplex-rs' features are incompatible. \
-Please select just one of the two.
+Please select just one of the two. If you need all compatible solvers, use the 'all_deafult_solvers' feature. \
 "
 );