src/regularisation.rs

/*!
Regularisation terms
*/

use serde::{Serialize, Deserialize};
use alg_tools::norms::Norm;
use alg_tools::linops::Apply;
use alg_tools::loc::Loc;
use crate::types::*;
use crate::measures::{
    DiscreteMeasure,
    Radon
};
#[allow(unused_imports)] // Used by documentation.
use crate::fb::generic_pointsource_fb_reg;

/// The regularisation term $α\\|μ\\|\_{ℳ(Ω)} + δ_{≥ 0}(μ)$ for [`generic_pointsource_fb_reg`].
///
/// The only member of the struct is the regularisation parameter α.
#[derive(Copy, Clone, Debug, Serialize, Deserialize)]
pub struct NonnegRadonRegTerm<F : Float>(pub F /* α */);

impl<'a, F : Float> NonnegRadonRegTerm<F> {
    /// Returns the regularisation parameter
    pub fn α(&self) -> F {
        let &NonnegRadonRegTerm(α) = self;
        α
    }
}

impl<'a, F : Float, const N : usize> Apply<&'a DiscreteMeasure<Loc<F, N>, F>>
for NonnegRadonRegTerm<F> {
    type Output = F;
    
    fn apply(&self, μ : &'a DiscreteMeasure<Loc<F, N>, F>) -> F {
        self.α() * μ.norm(Radon)
    }
}


/// The regularisation term $α\|μ\|_{ℳ(Ω)}$ for [`generic_pointsource_fb_reg`].
///
/// The only member of the struct is the regularisation parameter α.
#[derive(Copy, Clone, Debug, Serialize, Deserialize)]
pub struct RadonRegTerm<F : Float>(pub F /* α */);


impl<'a, F : Float> RadonRegTerm<F> {
    /// Returns the regularisation parameter
    pub fn α(&self) -> F {
        let &RadonRegTerm(α) = self;
        α
    }
}

impl<'a, F : Float, const N : usize> Apply<&'a DiscreteMeasure<Loc<F, N>, F>>
for RadonRegTerm<F> {
    type Output = F;
    
    fn apply(&self, μ : &'a DiscreteMeasure<Loc<F, N>, F>) -> F {
        self.α() * μ.norm(Radon)
    }
}

/// Regularisation term configuration
#[derive(Clone, Copy, Eq, PartialEq, Serialize, Deserialize, Debug)]
pub enum Regularisation<F : Float> {
    /// $α \\|μ\\|\_{ℳ(Ω)}$
    Radon(F),
    /// $α\\|μ\\|\_{ℳ(Ω)} + δ_{≥ 0}(μ)$
    NonnegRadon(F),
}

impl<'a, F : Float, const N : usize> Apply<&'a DiscreteMeasure<Loc<F, N>, F>>
for Regularisation<F> {
    type Output = F;
    
    fn apply(&self, μ : &'a DiscreteMeasure<Loc<F, N>, F>) -> F {
        match *self {
            Self::Radon(α) => RadonRegTerm(α).apply(μ),
            Self::NonnegRadon(α) => NonnegRadonRegTerm(α).apply(μ),
        }
    }
}