src/prox_penalty/wave.rs

branch
dev
changeset 37
c5d8bd1a7728
child 39
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equal deleted inserted replaced
36:fb911f72e698 37:c5d8bd1a7728
1 /*!
2 Basic proximal penalty based on convolution operators $𝒟$.
3 */
4
5 use numeric_literals::replace_float_literals;
6 use nalgebra::DVector;
7 use colored::Colorize;
8
9 use alg_tools::types::*;
10 use alg_tools::loc::Loc;
11 use alg_tools::mapping::{Mapping, RealMapping};
12 use alg_tools::nalgebra_support::ToNalgebraRealField;
13 use alg_tools::norms::Linfinity;
14 use alg_tools::iterate::{
15 AlgIteratorIteration,
16 AlgIterator,
17 };
18 use alg_tools::bisection_tree::{
19 BTFN,
20 PreBTFN,
21 Bounds,
22 BTSearch,
23 SupportGenerator,
24 LocalAnalysis,
25 BothGenerators,
26 };
27 use crate::measures::{
28 RNDM,
29 DeltaMeasure,
30 Radon,
31 };
32 use crate::measures::merging::{
33 SpikeMerging,
34 };
35 use crate::seminorms::DiscreteMeasureOp;
36 use crate::types::{
37 IterInfo,
38 };
39 use crate::measures::merging::SpikeMergingMethod;
40 use crate::regularisation::RegTerm;
41 use super::{ProxPenalty, FBGenericConfig};
42
43 #[replace_float_literals(F::cast_from(literal))]
44 impl<F, GA, BTA, S, Reg, 𝒟, G𝒟, K, const N : usize>
45 ProxPenalty<F, BTFN<F, GA, BTA, N>, Reg, N> for 𝒟
46 where
47 F : Float + ToNalgebraRealField,
48 GA : SupportGenerator<F, N, SupportType = S, Id = usize> + Clone,
49 BTA : BTSearch<F, N, Data=usize, Agg=Bounds<F>>,
50 S: RealMapping<F, N> + LocalAnalysis<F, Bounds<F>, N>,
51 G𝒟 : SupportGenerator<F, N, SupportType = K, Id = usize> + Clone,
52 𝒟 : DiscreteMeasureOp<Loc<F, N>, F, PreCodomain = PreBTFN<F, G𝒟, N>>,
53 𝒟::Codomain : RealMapping<F, N>,
54 K : RealMapping<F, N> + LocalAnalysis<F, Bounds<F>, N>,
55 Reg : RegTerm<F, N>,
56 RNDM<F, N> : SpikeMerging<F>,
57 {
58 type ReturnMapping = BTFN<F, BothGenerators<GA, G𝒟>, BTA, N>;
59
60 fn insert_and_reweigh<I>(
61 &self,
62 μ : &mut RNDM<F, N>,
63 τv : &mut BTFN<F, GA, BTA, N>,
64 μ_base : &RNDM<F, N>,
65 ν_delta: Option<&RNDM<F, N>>,
66 τ : F,
67 ε : F,
68 config : &FBGenericConfig<F>,
69 reg : &Reg,
70 state : &AlgIteratorIteration<I>,
71 stats : &mut IterInfo<F, N>,
72 ) -> (Option<BTFN<F, BothGenerators<GA, G𝒟>, BTA, N>>, bool)
73 where
74 I : AlgIterator
75 {
76
77 // TODO: is this inefficient to do in every iteration?
78 let op𝒟norm = self.opnorm_bound(Radon, Linfinity);
79
80 // Maximum insertion count and measure difference calculation depend on insertion style.
81 let (max_insertions, warn_insertions) = match (state.iteration(), config.bootstrap_insertions) {
82 (i, Some((l, k))) if i <= l => (k, false),
83 _ => (config.max_insertions, !state.is_quiet()),
84 };
85
86 let ω0 = match ν_delta {
87 None => self.apply(μ_base),
88 Some(ν) => self.apply(μ_base + ν),
89 };
90
91 // Add points to support until within error tolerance or maximum insertion count reached.
92 let mut count = 0;
93 let (within_tolerances, d) = 'insertion: loop {
94 if μ.len() > 0 {
95 // Form finite-dimensional subproblem. The subproblem references to the original μ^k
96 // from the beginning of the iteration are all contained in the immutable c and g.
97 // TODO: observe negation of -τv after switch from minus_τv: finite-dimensional
98 // problems have not yet been updated to sign change.
99 let à = self.findim_matrix(μ.iter_locations());
100 let g̃ = DVector::from_iterator(μ.len(),
101 μ.iter_locations()
102 .map(|ζ| ω0.apply(ζ) - τv.apply(ζ))
103 .map(F::to_nalgebra_mixed));
104 let mut x = μ.masses_dvector();
105
106 // The gradient of the forward component of the inner objective is C^*𝒟Cx - g̃.
107 // We have |C^*𝒟Cx|_2 = sup_{|z|_2 ≤ 1} ⟨z, C^*𝒟Cx⟩ = sup_{|z|_2 ≤ 1} ⟨Cz|𝒟Cx⟩
108 // ≤ sup_{|z|_2 ≤ 1} |Cz|_ℳ |𝒟Cx|_∞ ≤ sup_{|z|_2 ≤ 1} |Cz|_ℳ |𝒟| |Cx|_ℳ
109 // ≤ sup_{|z|_2 ≤ 1} |z|_1 |𝒟| |x|_1 ≤ sup_{|z|_2 ≤ 1} n |z|_2 |𝒟| |x|_2
110 // = n |𝒟| |x|_2, where n is the number of points. Therefore
111 let Ã_normest = op𝒟norm * F::cast_from(μ.len());
112
113 // Solve finite-dimensional subproblem.
114 stats.inner_iters += reg.solve_findim(&Ã, &g̃, τ, &mut x, Ã_normest, ε, config);
115
116 // Update masses of μ based on solution of finite-dimensional subproblem.
117 μ.set_masses_dvector(&x);
118 }
119
120 // Form d = τv + 𝒟μ - ω0 = τv + 𝒟(μ - μ^k) for checking the proximate optimality
121 // conditions in the predual space, and finding new points for insertion, if necessary.
122 let mut d = &*τv + match ν_delta {
123 None => self.preapply(μ.sub_matching(μ_base)),
124 Some(ν) => self.preapply(μ.sub_matching(μ_base) - ν)
125 };
126
127 // If no merging heuristic is used, let's be more conservative about spike insertion,
128 // and skip it after first round. If merging is done, being more greedy about spike
129 // insertion also seems to improve performance.
130 let skip_by_rough_check = if let SpikeMergingMethod::None = config.merging {
131 false
132 } else {
133 count > 0
134 };
135
136 // Find a spike to insert, if needed
137 let (ξ, _v_ξ, in_bounds) = match reg.find_tolerance_violation(
138 &mut d, τ, ε, skip_by_rough_check, config
139 ) {
140 None => break 'insertion (true, d),
141 Some(res) => res,
142 };
143
144 // Break if maximum insertion count reached
145 if count >= max_insertions {
146 break 'insertion (in_bounds, d)
147 }
148
149 // No point in optimising the weight here; the finite-dimensional algorithm is fast.
150 *μ += DeltaMeasure { x : ξ, α : 0.0 };
151 count += 1;
152 stats.inserted += 1;
153 };
154
155 if !within_tolerances && warn_insertions {
156 // Complain (but continue) if we failed to get within tolerances
157 // by inserting more points.
158 let err = format!("Maximum insertions reached without achieving \
159 subproblem solution tolerance");
160 println!("{}", err.red());
161 }
162
163 (Some(d), within_tolerances)
164 }
165
166 fn merge_spikes(
167 &self,
168 μ : &mut RNDM<F, N>,
169 τv : &mut BTFN<F, GA, BTA, N>,
170 μ_base : &RNDM<F, N>,
171 τ : F,
172 ε : F,
173 config : &FBGenericConfig<F>,
174 reg : &Reg,
175 ) -> usize
176 {
177 μ.merge_spikes(config.merging, |μ_candidate| {
178 let mut d = &*τv + self.preapply(μ_candidate.sub_matching(μ_base));
179 reg.verify_merge_candidate(&mut d, μ_candidate, τ, ε, config)
180 })
181 }
182 }

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