Remove unused delta box operators

[geoffroyleconte]

For NormL0Box and NormL1Box.

This will be breaking for box operators because shifted(h, x, l, u, Δ) becomes shifted(h, x, l, u), and set_radius! will no longer work (it did not really updated the trust region before but will now return an error message indicating that there is no field Δ, set_bounds! should be used instead). I think that Δ was not used in these shifted operators.

[codecov[bot]]

Codecov Report

Base: 61.79% // Head: 62.00% // Increases project coverage by +0.21% :tada:

Coverage data is based on head (854b51a) compared to base (0b94cfa). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #99 +/- ## ========================================== + Coverage 61.79% 62.00% +0.21% ========================================== Files 22 22 Lines 657 658 +1 ========================================== + Hits 406 408 +2 + Misses 251 250 -1 ``` | [Impacted Files](https://codecov.io/gh/JuliaSmoothOptimizers/ShiftedProximalOperators.jl/pull/99?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers) | Coverage Δ | | |---|---|---| | [src/shiftedNormL0Box.jl](https://codecov.io/gh/JuliaSmoothOptimizers/ShiftedProximalOperators.jl/pull/99?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers#diff-c3JjL3NoaWZ0ZWROb3JtTDBCb3guamw=) | `91.30% <100.00%> (ø)` | | | [src/shiftedNormL1Box.jl](https://codecov.io/gh/JuliaSmoothOptimizers/ShiftedProximalOperators.jl/pull/99?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers#diff-c3JjL3NoaWZ0ZWROb3JtTDFCb3guamw=) | `90.24% <100.00%> (ø)` | | | [src/ShiftedProximalOperators.jl](https://codecov.io/gh/JuliaSmoothOptimizers/ShiftedProximalOperators.jl/pull/99?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers#diff-c3JjL1NoaWZ0ZWRQcm94aW1hbE9wZXJhdG9ycy5qbA==) | `72.22% <0.00%> (+3.65%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers)

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[dpo]

If ∆ is not used, it's a bug. Those operators should include the indicator of [ℓ, u] ⋂ ∆𝔹.

[geoffroyleconte]

If ∆ is not used, it's a bug. Those operators should include the indicator of [ℓ, u] ⋂ ∆𝔹.

You used shifted(h, xk, max.(-Δk, l_bound - xk), min.(Δk, u_bound - xk), Δk, selected) in https://github.com/JuliaSmoothOptimizers/RegularizedOptimization.jl/pull/81

Should I understand that you want to use this instead: shifted(h, xk, l_bound - xk, u_bound - xk, Δk, selected)? With the current state of this PR it changes to shifted(h, xk, max.(-Δk, l_bound - xk), min.(Δk, u_bound - xk), selected).

I think the first solution implies calling max internally anyways. And some algorithms don't need $\Delta \mathbb{B}$ (R2 for example). I just want to make sure that it is the right thing to implement before changing everything, and my PR for the iprox is also based on the same design.

[dpo]

You used shifted(h, xk, max.(-Δk, l_bound - xk), min.(Δk, u_bound - xk), Δk, selected)

Ah yes, you're right. The way it is now is right because we can use the same box operators with R2 when there are bound constraints.

[dpo]

thank you