MFEM v4.7.0
Finite element discretization library
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transformation.cpp
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1// Copyright (c) 2010-2024, Lawrence Livermore National Security, LLC. Produced
2// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
3// LICENSE and NOTICE for details. LLNL-CODE-806117.
4//
5// This file is part of the MFEM library. For more information and source code
6// availability visit https://mfem.org.
7//
8// MFEM is free software; you can redistribute it and/or modify it under the
9// terms of the BSD-3 license. We welcome feedback and contributions, see file
10// CONTRIBUTING.md for details
11
12#include "transformation.hpp"
13#include <cmath>
14#include <functional>
15
16namespace mfem
17{
18namespace spde
19{
20
21// ---------------------------------------------------------------------------
22// Functions for TransformedCoefficient interface
23// ---------------------------------------------------------------------------
24
25/// This function effectively implements equation 19 of the paper (see header).
26/// `\Phi [y(x)]`
27real_t TransformToUniform(real_t x) { return std::erfc(-x / std::sqrt(2)) / 2; }
28
29real_t ApplyLevelSetAtZero(real_t x) { return x >= 0 ? 1 : 0; }
30
31// ---------------------------------------------------------------------------
32// Member functions for GFTransformer class
33// ---------------------------------------------------------------------------
34
36{
37 GridFunctionCoefficient gf_coeff(&x);
38 ConstantCoefficient factor(max_ - min_);
39 ConstantCoefficient summand(min_);
40 TransformedCoefficient transformation_coeff(&gf_coeff, TransformToUniform);
41 ProductCoefficient product_coeff(transformation_coeff, factor);
42 SumCoefficient sum_coeff(product_coeff, summand);
43 ParGridFunction xx(x);
44 xx.ProjectCoefficient(sum_coeff);
45 x = xx;
46}
47
49{
50 ConstantCoefficient offset(offset_);
51 ParGridFunction xx(x);
52 xx.ProjectCoefficient(offset);
53 x += xx;
54}
55
56void ScaleTransformer::Transform(ParGridFunction &x) const { x *= scale_; }
57
59{
60 GridFunctionCoefficient gf_coeff(&x);
61 ConstantCoefficient threshold(-threshold_);
62 SumCoefficient sum_coeff(gf_coeff, threshold);
63 TransformedCoefficient transformation_coeff(&sum_coeff, ApplyLevelSetAtZero);
64 ParGridFunction xx(x);
65 xx.ProjectCoefficient(transformation_coeff);
66 x = xx;
67}
68
69} // namespace spde
70} // namespace mfem
A coefficient that is constant across space and time.
Definition: coefficient.hpp:85
Coefficient defined by a GridFunction. This coefficient is mesh dependent.
Class for parallel grid function.
Definition: pgridfunc.hpp:33
void ProjectCoefficient(Coefficient &coeff) override
Project coeff Coefficient to this GridFunction. The projection computation depends on the choice of t...
Definition: pgridfunc.cpp:562
Scalar coefficient defined as the product of two scalar coefficients or a scalar and a scalar coeffic...
Scalar coefficient defined as the linear combination of two scalar coefficients or a scalar and a sca...
A coefficient that depends on 1 or 2 parent coefficients and a transformation rule represented by a C...
void Transform(ParGridFunction &x) const override
Applies a level set to the GridFunction.
void Transform(ParGridFunction &x) const override
Offsets a grid function by an constant offset.
void Transform(ParGridFunction &x) const override
Scales a grid function by an constant factor.
void Transform(ParGridFunction &x) const override
real_t ApplyLevelSetAtZero(real_t x)
real_t TransformToUniform(real_t x)
float real_t
Definition: config.hpp:43