src/prox_penalty/wave.rs

changeset 52
f0e8704d3f0e
parent 39
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equal deleted inserted replaced
31:6105b5cd8d89 52:f0e8704d3f0e
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::regularisation::RegTerm;
40 use super::{ProxPenalty, FBGenericConfig};
41
42 #[replace_float_literals(F::cast_from(literal))]
43 impl<F, GA, BTA, S, Reg, 𝒟, G𝒟, K, const N : usize>
44 ProxPenalty<F, BTFN<F, GA, BTA, N>, Reg, N> for 𝒟
45 where
46 F : Float + ToNalgebraRealField,
47 GA : SupportGenerator<F, N, SupportType = S, Id = usize> + Clone,
48 BTA : BTSearch<F, N, Data=usize, Agg=Bounds<F>>,
49 S: RealMapping<F, N> + LocalAnalysis<F, Bounds<F>, N>,
50 G𝒟 : SupportGenerator<F, N, SupportType = K, Id = usize> + Clone,
51 𝒟 : DiscreteMeasureOp<Loc<F, N>, F, PreCodomain = PreBTFN<F, G𝒟, N>>,
52 𝒟::Codomain : RealMapping<F, N>,
53 K : RealMapping<F, N> + LocalAnalysis<F, Bounds<F>, N>,
54 Reg : RegTerm<F, N>,
55 RNDM<F, N> : SpikeMerging<F>,
56 {
57 type ReturnMapping = BTFN<F, BothGenerators<GA, G𝒟>, BTA, N>;
58
59 fn insert_and_reweigh<I>(
60 &self,
61 μ : &mut RNDM<F, N>,
62 τv : &mut BTFN<F, GA, BTA, N>,
63 μ_base : &RNDM<F, N>,
64 ν_delta: Option<&RNDM<F, N>>,
65 τ : F,
66 ε : F,
67 config : &FBGenericConfig<F>,
68 reg : &Reg,
69 state : &AlgIteratorIteration<I>,
70 stats : &mut IterInfo<F, N>,
71 ) -> (Option<BTFN<F, BothGenerators<GA, G𝒟>, BTA, N>>, bool)
72 where
73 I : AlgIterator
74 {
75
76 let op𝒟norm = self.opnorm_bound(Radon, Linfinity);
77
78 // Maximum insertion count and measure difference calculation depend on insertion style.
79 let (max_insertions, warn_insertions) = match (state.iteration(), config.bootstrap_insertions) {
80 (i, Some((l, k))) if i <= l => (k, false),
81 _ => (config.max_insertions, !state.is_quiet()),
82 };
83
84 let ω0 = match ν_delta {
85 None => self.apply(μ_base),
86 Some(ν) => self.apply(μ_base + ν),
87 };
88
89 // Add points to support until within error tolerance or maximum insertion count reached.
90 let mut count = 0;
91 let (within_tolerances, d) = 'insertion: loop {
92 if μ.len() > 0 {
93 // Form finite-dimensional subproblem. The subproblem references to the original μ^k
94 // from the beginning of the iteration are all contained in the immutable c and g.
95 // TODO: observe negation of -τv after switch from minus_τv: finite-dimensional
96 // problems have not yet been updated to sign change.
97 let à = self.findim_matrix(μ.iter_locations());
98 let g̃ = DVector::from_iterator(μ.len(),
99 μ.iter_locations()
100 .map(|ζ| ω0.apply(ζ) - τv.apply(ζ))
101 .map(F::to_nalgebra_mixed));
102 let mut x = μ.masses_dvector();
103
104 // The gradient of the forward component of the inner objective is C^*𝒟Cx - g̃.
105 // We have |C^*𝒟Cx|_2 = sup_{|z|_2 ≤ 1} ⟨z, C^*𝒟Cx⟩ = sup_{|z|_2 ≤ 1} ⟨Cz|𝒟Cx⟩
106 // ≤ sup_{|z|_2 ≤ 1} |Cz|_ℳ |𝒟Cx|_∞ ≤ sup_{|z|_2 ≤ 1} |Cz|_ℳ |𝒟| |Cx|_ℳ
107 // ≤ sup_{|z|_2 ≤ 1} |z|_1 |𝒟| |x|_1 ≤ sup_{|z|_2 ≤ 1} n |z|_2 |𝒟| |x|_2
108 // = n |𝒟| |x|_2, where n is the number of points. Therefore
109 let Ã_normest = op𝒟norm * F::cast_from(μ.len());
110
111 // Solve finite-dimensional subproblem.
112 stats.inner_iters += reg.solve_findim(&Ã, &g̃, τ, &mut x, Ã_normest, ε, config);
113
114 // Update masses of μ based on solution of finite-dimensional subproblem.
115 μ.set_masses_dvector(&x);
116 }
117
118 // Form d = τv + 𝒟μ - ω0 = τv + 𝒟(μ - μ^k) for checking the proximate optimality
119 // conditions in the predual space, and finding new points for insertion, if necessary.
120 let mut d = &*τv + match ν_delta {
121 None => self.preapply(μ.sub_matching(μ_base)),
122 Some(ν) => self.preapply(μ.sub_matching(μ_base) - ν)
123 };
124
125 // If no merging heuristic is used, let's be more conservative about spike insertion,
126 // and skip it after first round. If merging is done, being more greedy about spike
127 // insertion also seems to improve performance.
128 let skip_by_rough_check = if config.merging.enabled {
129 false
130 } else {
131 count > 0
132 };
133
134 // Find a spike to insert, if needed
135 let (ξ, _v_ξ, in_bounds) = match reg.find_tolerance_violation(
136 &mut d, τ, ε, skip_by_rough_check, config
137 ) {
138 None => break 'insertion (true, d),
139 Some(res) => res,
140 };
141
142 // Break if maximum insertion count reached
143 if count >= max_insertions {
144 break 'insertion (in_bounds, d)
145 }
146
147 // No point in optimising the weight here; the finite-dimensional algorithm is fast.
148 *μ += DeltaMeasure { x : ξ, α : 0.0 };
149 count += 1;
150 stats.inserted += 1;
151 };
152
153 if !within_tolerances && warn_insertions {
154 // Complain (but continue) if we failed to get within tolerances
155 // by inserting more points.
156 let err = format!("Maximum insertions reached without achieving \
157 subproblem solution tolerance");
158 println!("{}", err.red());
159 }
160
161 (Some(d), within_tolerances)
162 }
163
164 fn merge_spikes(
165 &self,
166 μ : &mut RNDM<F, N>,
167 τv : &mut BTFN<F, GA, BTA, N>,
168 μ_base : &RNDM<F, N>,
169 ν_delta: Option<&RNDM<F, N>>,
170 τ : F,
171 ε : F,
172 config : &FBGenericConfig<F>,
173 reg : &Reg,
174 fitness : Option<impl Fn(&RNDM<F, N>) -> F>,
175 ) -> usize
176 {
177 if config.fitness_merging {
178 if let Some(f) = fitness {
179 return μ.merge_spikes_fitness(config.merging, f, |&v| v)
180 .1
181 }
182 }
183 μ.merge_spikes(config.merging, |μ_candidate| {
184 let mut d = &*τv + self.preapply(match ν_delta {
185 None => μ_candidate.sub_matching(μ_base),
186 Some(ν) => μ_candidate.sub_matching(μ_base) - ν,
187 });
188 reg.verify_merge_candidate(&mut d, μ_candidate, τ, ε, config)
189 })
190 }
191 }

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