Add a simple example

fmm/examples/single_node.rs

@@ -0,0 +1,60 @@
+use std::time::Instant;
+
+use itertools::Itertools;
+
+use rlst_dense::rlst_array_from_slice2;
+use rlst_dense::traits::RawAccess;
+
+use bempp_field::types::{FftFieldTranslationKiFmm, SvdFieldTranslationKiFmm};
+use bempp_kernel::laplace_3d::Laplace3dKernel;
+use bempp_tree::implementations::helpers::{points_fixture, points_fixture_sphere};
+use bempp_tree::{constants::ROOT, types::single_node::SingleNodeTree};
+use bempp_fmm::{types::{KiFmmLinear, FmmDataUniform}, charge::build_charge_dict};
+use bempp_traits::{
+    field::{FieldTranslation, FieldTranslationData},
+    fmm::{Fmm, FmmLoop, KiFmm as KiFmmTrait, SourceTranslation, TargetTranslation, TimeDict},
+    kernel::{Kernel, ScaleInvariantKernel},
+    tree::Tree,
+    types::EvalType,
+};
+
+
+fn main () {
+
+        let npoints = 1000000;
+
+        let points = points_fixture::<f64>(npoints, None, None);
+
+        let global_idxs = (0..npoints).collect_vec();
+        let charges = vec![1.0; npoints];
+
+        let order = 6;
+        let alpha_inner = 1.05;
+        let alpha_outer = 2.95;
+        let depth = 4;
+
+        let tree = SingleNodeTree::new(points.data(), false, None, Some(depth), &global_idxs, true);
+
+        let kernel = Laplace3dKernel::default();
+        let m2l_data: FftFieldTranslationKiFmm<f64, Laplace3dKernel<f64>> =
+            FftFieldTranslationKiFmm::new(kernel.clone(), order, *tree.get_domain(), alpha_inner);
+        // let m2l_data = SvdFieldTranslationKiFmm::new(
+        //     kernel.clone(),
+        //     Some(50),
+        //     order,
+        //     *tree.get_domain(),
+        //     alpha_inner,
+        // );
+
+        let fmm = KiFmmLinear::new(order, alpha_inner, alpha_outer, kernel, tree, m2l_data);
+
+        // Form charge dict, matching charges with their associated global indices
+        let charge_dict = build_charge_dict(&global_idxs, &charges);
+
+        let datatree = FmmDataUniform::new(fmm, &charge_dict).unwrap();
+
+        let s = Instant::now();
+        let times = datatree.run(true);
+        println!("runtime {:?} operators {:?}", s.elapsed(), times);
+
+}