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annotate src/SbpOperators/volumeops/derivatives/second_derivative_variable.jl @ 906:33c7e266e1a9 feature/variable_derivatives

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Add fix for type instability in SecondDerivativeVariable along with tests
author Jonatan Werpers <jonatan@werpers.com>
date Tue, 15 Feb 2022 09:56:07 +0100
parents 5bbc3ea3821b
children cad3a9f82009
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1 export SecondDerivativeVariable
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2
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3 # """
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4 # SecondDerivativeVariable(grid, inner_stencil, closure_stencils, parity, direction)
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5
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6 # Creates a volume operator on a `Dim`-dimensional grid acting along the
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7 # specified coordinate `direction`. The action of the operator is determined by
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8 # the stencils `inner_stencil` and `closure_stencils`. When `Dim=1`, the
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9 # corresponding `SecondDerivativeVariable` tensor mapping is returned. When `Dim>1`, the
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10 # returned operator is the appropriate outer product of a one-dimensional
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11 # operators and `IdentityMapping`s, e.g for `Dim=3` the volume operator in the
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12 # y-direction is `I⊗op⊗I`.
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13 # """
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14 # function volume_operator(grid::EquidistantGrid, inner_stencil, closure_stencils, parity, direction)
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15 # #TODO: Check that direction <= Dim?
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16
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17 # # Create 1D volume operator in along coordinate direction
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18 # op = SecondDerivativeVariable(restrict(grid, direction), inner_stencil, closure_stencils, parity)
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19 # # Create 1D IdentityMappings for each coordinate direction
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20 # one_d_grids = restrict.(Ref(grid), Tuple(1:dimension(grid)))
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21 # Is = IdentityMapping{eltype(grid)}.(size.(one_d_grids))
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22 # # Formulate the correct outer product sequence of the identity mappings and
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23 # # the volume operator
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24 # parts = Base.setindex(Is, op, direction)
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25 # return foldl(⊗, parts)
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26 # end
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27
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28 """
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29 SecondDerivativeVariable{T,N,M,K} <: TensorOperator{T,1}
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30
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31 Implements the one-dimensional second derivative with variable coefficients.
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32 """
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33 struct SecondDerivativeVariable{Dir,T,D,M,IStencil<:NestedStencil{T},CStencil<:NestedStencil{T},TArray<:AbstractArray} <: TensorMapping{T,D,D}
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34 inner_stencil::IStencil
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35 closure_stencils::NTuple{M,CStencil}
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36 size::NTuple{D,Int}
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37 coefficient::TArray
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38
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39 function SecondDerivativeVariable{Dir, D}(inner_stencil::NestedStencil{T}, closure_stencils::NTuple{M,NestedStencil{T}}, size::NTuple{D,Int}, coefficient::AbstractArray) where {Dir,T,D,M}
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40 IStencil = typeof(inner_stencil)
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41 CStencil = eltype(closure_stencils)
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42 TArray = typeof(coefficient)
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43 return new{Dir,T,D,M,IStencil,CStencil,TArray}(inner_stencil,closure_stencils,size, coefficient)
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44 end
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45 end
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46
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47 function SecondDerivativeVariable(grid::EquidistantGrid, coeff::AbstractArray, inner_stencil, closure_stencils, dir)
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48 Δxᵢ = spacing(grid)[dir]
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49 scaled_inner_stencil = scale(inner_stencil, 1/Δxᵢ^2)
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50 scaled_closure_stencils = scale.(Tuple(closure_stencils), 1/Δxᵢ^2)
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51 return SecondDerivativeVariable{dir, dimension(grid)}(scaled_inner_stencil, scaled_closure_stencils, size(grid), coeff)
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52 end
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53
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54 function SecondDerivativeVariable(grid::EquidistantGrid{1}, coeff::AbstractVector, inner_stencil, closure_stencils)
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55 return SecondDerivativeVariable(grid, coeff, inner_stencil, closure_stencils, 1)
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56 end
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57
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58 function SecondDerivativeVariable(grid::EquidistantGrid, coeff::AbstractArray, stencil_set, dir)
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59 inner_stencil = parse_nested_stencil(eltype(coeff), stencil_set["D2variable"]["inner_stencil"])
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60 closure_stencils = parse_nested_stencil.(eltype(coeff), stencil_set["D2variable"]["closure_stencils"])
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61
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62 return SecondDerivativeVariable(grid, coeff, inner_stencil, closure_stencils, dir)
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63 end
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64
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65 derivative_direction(::SecondDerivativeVariable{Dir}) where {Dir} = Dir
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66
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67 closure_size(op::SecondDerivativeVariable) = length(op.closure_stencils)
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68
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69 LazyTensors.range_size(op::SecondDerivativeVariable) = op.size
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70 LazyTensors.domain_size(op::SecondDerivativeVariable) = op.size
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71
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72
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73 function derivative_view(op, a, I)
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74 d = derivative_direction(op)
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75
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76 Iview = Base.setindex(I,:,d)
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77 return @view a[Iview...]
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78
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79 # D = domain_dim(op)
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80 # Iₗ, _, Iᵣ = split_tuple(I, Val(d-1), Val(1), Val(D-d))
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81 # return @view a[Iₗ..., :, Iᵣ...]
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82 end
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83
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84 function apply_lower(op::SecondDerivativeVariable, v, I...)
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85 ṽ = derivative_view(op, v, I)
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86 c̃ = derivative_view(op, op.coefficient, I)
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87
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88 i = I[derivative_direction(op)]
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89 return @inbounds apply_stencil(op.closure_stencils[i], c̃, ṽ, i)
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90 end
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91
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92 function apply_interior(op::SecondDerivativeVariable, v, I...)
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93 ṽ = derivative_view(op, v, I)
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94 c̃ = derivative_view(op, op.coefficient, I)
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95
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96 i = I[derivative_direction(op)]
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97 return apply_stencil(op.inner_stencil, c̃, ṽ, i)
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98 end
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99
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100 function apply_upper(op::SecondDerivativeVariable, v, I...)
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101 ṽ = derivative_view(op, v, I)
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102 c̃ = derivative_view(op, op.coefficient, I)
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103
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104 i = I[derivative_direction(op)]
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105 stencil = op.closure_stencils[op.size[derivative_direction(op)]-i+1]
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106 return @inbounds apply_stencil_backwards(stencil, c̃, ṽ, i)
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107 end
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108
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109 function LazyTensors.apply(op::SecondDerivativeVariable, v::AbstractArray, I::Vararg{Index})
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110 if I[derivative_direction(op)] isa Index{Lower}
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111 return apply_lower(op, v, Int.(I)...)
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112 elseif I[derivative_direction(op)] isa Index{Upper}
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113 return apply_upper(op, v, Int.(I)...)
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114 else
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115 return apply_interior(op, v, Int.(I)...)
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116 end
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117 end
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118
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119 function LazyTensors.apply(op::SecondDerivativeVariable, v::AbstractArray, I...)
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120 dir = derivative_direction(op)
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121
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122 i = I[dir]
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123 r = getregion(i, closure_size(op), op.size[dir])
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124
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125 I = map(i->Index(i, Interior), I)
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126 I = Base.setindex(I, Index(i, r), dir)
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127 return LazyTensors.apply(op, v, I...)
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128 end
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129
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130 # TODO: Rename SecondDerivativeVariable -> VariableSecondDerivative