From 611c8d87958a1c7585a690eee4f4ac55cc816f77 Mon Sep 17 00:00:00 2001
From: Timo Betcke <timo.betcke@gmail.com>
Date: Tue, 31 Dec 2024 19:50:46 +0100
Subject: [PATCH] WIP: Testing evaluators

---
 Cargo.toml                        |  3 +-
 examples/test_green_evaluators.rs | 60 +++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 examples/test_green_evaluators.rs

diff --git a/Cargo.toml b/Cargo.toml
index 58fdd422..9341f92a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,7 +38,8 @@ green-kernels = { git = "https://github.com/bempp/green-kernels.git", features =
 # c-api-tools = { version = "0.1.0" }
 kifmm = { git = "https://github.com/bempp/kifmm.git", features = ["mpi"] }
 bempp-distributed-tools = { git = "https://github.com/bempp/distributed_tools.git"}
-
+rand = "0.8"
+rand_chacha = "0.3"
 
 [dev-dependencies]
 approx = "0.5"
diff --git a/examples/test_green_evaluators.rs b/examples/test_green_evaluators.rs
new file mode 100644
index 00000000..2f93bb1a
--- /dev/null
+++ b/examples/test_green_evaluators.rs
@@ -0,0 +1,60 @@
+// Compare dense and FMM Green's function evaluators.
+
+use bempp::greens_function_evaluators::kifmm_evaluator::KiFmmEvaluator;
+use bempp_distributed_tools::IndexLayoutFromLocalCounts;
+use green_kernels::{laplace_3d::Laplace3dKernel, types::GreenKernelEvalType};
+use rand::{Rng, SeedableRng};
+use rand_chacha::ChaCha8Rng;
+use rlst::{operator::interface::DistributedArrayVectorSpace, Element, LinearSpace};
+
+fn main() {
+    // Number of points per process.
+    let npoints = 10000;
+    let mut rng = ChaCha8Rng::seed_from_u64(0);
+
+    // Create random sources and targets.
+
+    let sources = (0..3 * npoints)
+        .map(|_| rng.gen_range(-1.0..1.0))
+        .collect::<Vec<f64>>();
+
+    let targets = sources.clone();
+
+    // Initialise MPI
+
+    let universe = mpi::initialize().unwrap();
+    let world = universe.world();
+
+    // Initalise the index layout.
+
+    let index_layout = IndexLayoutFromLocalCounts::new(npoints, &world);
+
+    // Create the vector space.
+
+    let space = DistributedArrayVectorSpace::<_, f64>::new(&index_layout);
+
+    // Create a random vector of charges.
+
+    let mut charges = space.zero();
+
+    charges
+        .view_mut()
+        .local_mut()
+        .fill_from_equally_distributed(&mut rng);
+
+    // Create the dense evaluator.
+
+    let dense_evaluator = bempp::greens_function_evaluators::dense_evaluator::DenseEvaluator::new(
+        &sources,
+        &targets,
+        GreenKernelEvalType::Value,
+        false,
+        Laplace3dKernel::default(),
+        &space,
+        &space,
+    );
+
+    // Create the FMM evaluator.
+
+    let fmm_evaluator = KiFmmEvaluator::new(&sources, &targets, 3, 2, 10, &space, &space);
+}