xref: /libCEED/examples/rust/ex1-volume/src/transform.rs (revision 3d8e882215d238700cdceb37404f76ca7fa24eaa)
1*3d8e8822SJeremy L Thompson // Copyright (c) 2017-2022, Lawrence Livermore National Security, LLC and other CEED contributors.
2*3d8e8822SJeremy L Thompson // All Rights Reserved. See the top-level LICENSE and NOTICE files for details.
3ded9b81dSJeremy L Thompson //
4*3d8e8822SJeremy L Thompson // SPDX-License-Identifier: BSD-2-Clause
5ded9b81dSJeremy L Thompson //
6*3d8e8822SJeremy L Thompson // This file is part of CEED:  http://github.com/ceed
7ded9b81dSJeremy L Thompson 
8ded9b81dSJeremy L Thompson use libceed::prelude::*;
9ded9b81dSJeremy L Thompson 
10ded9b81dSJeremy L Thompson // ----------------------------------------------------------------------------
11ded9b81dSJeremy L Thompson // Transform mesh coordinates
12ded9b81dSJeremy L Thompson // ----------------------------------------------------------------------------
13ded9b81dSJeremy L Thompson pub(crate) fn transform_mesh_coordinates(
14ded9b81dSJeremy L Thompson     dim: usize,
15ded9b81dSJeremy L Thompson     mesh_size: usize,
16ded9b81dSJeremy L Thompson     mesh_coords: &mut Vector,
174d27c890SJeremy L Thompson ) -> libceed::Result<Scalar> {
18ded9b81dSJeremy L Thompson     // Transform coordinates
19ded9b81dSJeremy L Thompson     if dim == 1 {
20d3677ae8SJeremy L Thompson         for coord in mesh_coords.view_mut()?.iter_mut() {
21ded9b81dSJeremy L Thompson             // map [0,1] to [0,1] varying the mesh density
22ded9b81dSJeremy L Thompson             *coord = 0.5
2380a9ef05SNatalie Beams                 + 1.0 / (3.0 as Scalar).sqrt()
2480a9ef05SNatalie Beams                     * ((2.0 / 3.0) * std::f64::consts::PI as Scalar * (*coord - 0.5)).sin()
25d3677ae8SJeremy L Thompson         }
26ded9b81dSJeremy L Thompson     } else {
27e78171edSJeremy L Thompson         let mut coords = mesh_coords.view_mut()?;
28ded9b81dSJeremy L Thompson         let num_nodes = mesh_size / dim;
29ded9b81dSJeremy L Thompson         for i in 0..num_nodes {
30ded9b81dSJeremy L Thompson             // map (x,y) from [0,1]x[0,1] to the quarter annulus with polar
31ded9b81dSJeremy L Thompson             // coordinates, (r,phi) in [1,2]x[0,pi/2] with area = 3/4*pi
32ded9b81dSJeremy L Thompson             let u = 1.0 + coords[i];
3380a9ef05SNatalie Beams             let v = std::f64::consts::PI as Scalar / 2.0 * coords[i + num_nodes];
34ded9b81dSJeremy L Thompson             coords[i] = u * v.cos();
35ded9b81dSJeremy L Thompson             coords[i + num_nodes] = u * v.sin();
36ded9b81dSJeremy L Thompson         }
37ded9b81dSJeremy L Thompson     }
38ded9b81dSJeremy L Thompson 
39ded9b81dSJeremy L Thompson     // Exact volume of transformed region
40ded9b81dSJeremy L Thompson     let exact_volume = match dim {
41ded9b81dSJeremy L Thompson         1 => 1.0,
4280a9ef05SNatalie Beams         _ => 3.0 / 4.0 * std::f64::consts::PI as Scalar,
43ded9b81dSJeremy L Thompson     };
44e78171edSJeremy L Thompson     Ok(exact_volume)
45ded9b81dSJeremy L Thompson }
46ded9b81dSJeremy L Thompson 
47ded9b81dSJeremy L Thompson // ----------------------------------------------------------------------------
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