diff -r 9738b51d90d7 -r 4f468d35fa29 src/kernels/gaussian.rs
--- a/src/kernels/gaussian.rs	Sun Apr 27 15:03:51 2025 -0500
+++ b/src/kernels/gaussian.rs	Thu Feb 26 11:38:43 2026 -0500
@@ -1,58 +1,51 @@
 //! Implementation of the gaussian kernel.
 
+use alg_tools::bisection_tree::{Constant, Support, Weighted};
+use alg_tools::bounds::{Bounded, Bounds, GlobalAnalysis, LocalAnalysis};
+use alg_tools::euclidean::Euclidean;
+use alg_tools::loc::Loc;
+use alg_tools::mapping::{
+    DifferentiableImpl, Differential, Instance, LipschitzDifferentiableImpl, Mapping,
+};
+use alg_tools::maputil::array_init;
+use alg_tools::norms::*;
+use alg_tools::sets::Cube;
+use alg_tools::types::*;
 use float_extras::f64::erf;
 use numeric_literals::replace_float_literals;
 use serde::Serialize;
-use alg_tools::types::*;
-use alg_tools::euclidean::Euclidean;
-use alg_tools::norms::*;
-use alg_tools::loc::Loc;
-use alg_tools::sets::Cube;
-use alg_tools::bisection_tree::{
-    Support,
-    Constant,
-    Bounds,
-    LocalAnalysis,
-    GlobalAnalysis,
-    Weighted,
-    Bounded,
-};
-use alg_tools::mapping::{
-    Mapping,
-    Instance,
-    Differential,
-    DifferentiableImpl,
-};
-use alg_tools::maputil::array_init;
 
-use crate::types::*;
+use super::ball_indicator::CubeIndicator;
+use super::base::*;
 use crate::fourier::Fourier;
-use super::base::*;
-use super::ball_indicator::CubeIndicator;
+use crate::types::*;
 
 /// Storage presentation of the the anisotropic gaussian kernel of `variance` $σ^2$.
 ///
 /// This is the function $f(x) = C e^{-\\|x\\|\_2^2/(2σ^2)}$ for $x ∈ ℝ^N$
 /// with $C=1/(2πσ^2)^{N/2}$.
-#[derive(Copy,Clone,Debug,Serialize,Eq)]
-pub struct Gaussian<S : Constant, const N : usize> {
+#[derive(Copy, Clone, Debug, Serialize, Eq)]
+pub struct Gaussian<S: Constant, const N: usize> {
     /// The variance $σ^2$.
-    pub variance : S,
+    pub variance: S,
 }
 
-impl<S1, S2, const N : usize> PartialEq<Gaussian<S2, N>> for Gaussian<S1, N>
-where S1 : Constant,
-      S2 : Constant<Type=S1::Type> {
-    fn eq(&self, other : &Gaussian<S2, N>) -> bool {
+impl<S1, S2, const N: usize> PartialEq<Gaussian<S2, N>> for Gaussian<S1, N>
+where
+    S1: Constant,
+    S2: Constant<Type = S1::Type>,
+{
+    fn eq(&self, other: &Gaussian<S2, N>) -> bool {
         self.variance.value() == other.variance.value()
     }
 }
 
-impl<S1, S2, const N : usize> PartialOrd<Gaussian<S2, N>> for Gaussian<S1, N>
-where S1 : Constant,
-      S2 : Constant<Type=S1::Type> {
-
-    fn partial_cmp(&self, other : &Gaussian<S2, N>) -> Option<std::cmp::Ordering> {
+impl<S1, S2, const N: usize> PartialOrd<Gaussian<S2, N>> for Gaussian<S1, N>
+where
+    S1: Constant,
+    S2: Constant<Type = S1::Type>,
+{
+    fn partial_cmp(&self, other: &Gaussian<S2, N>) -> Option<std::cmp::Ordering> {
         // A gaussian is ≤ another gaussian if the Fourier transforms satisfy the
         // corresponding inequality. That in turns holds if and only if the variances
         // satisfy the opposite inequality.
@@ -62,18 +55,17 @@
     }
 }
 
-
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<'a, S, const N : usize> Mapping<Loc<S::Type, N>> for Gaussian<S, N>
+impl<'a, S, const N: usize> Mapping<Loc<N, S::Type>> for Gaussian<S, N>
 where
-    S : Constant
+    S: Constant,
 {
     type Codomain = S::Type;
 
     // This is not normalised to neither to have value 1 at zero or integral 1
     // (unless the cut-off ε=0).
     #[inline]
-    fn apply<I : Instance<Loc<S::Type, N>>>(&self, x : I) -> Self::Codomain {
+    fn apply<I: Instance<Loc<N, S::Type>>>(&self, x: I) -> Self::Codomain {
         let d_squared = x.eval(|x| x.norm2_squared());
         let σ2 = self.variance.value();
         let scale = self.scale();
@@ -82,19 +74,20 @@
 }
 
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<'a, S, const N : usize> DifferentiableImpl<Loc<S::Type, N>> for Gaussian<S, N>
-where S : Constant {
-    type Derivative = Loc<S::Type, N>;
+impl<'a, S, const N: usize> DifferentiableImpl<Loc<N, S::Type>> for Gaussian<S, N>
+where
+    S: Constant,
+{
+    type Derivative = Loc<N, S::Type>;
 
     #[inline]
-    fn differential_impl<I : Instance<Loc<S::Type, N>>>(&self, x0 : I) -> Self::Derivative {
-        let x = x0.cow();
+    fn differential_impl<I: Instance<Loc<N, S::Type>>>(&self, x0: I) -> Self::Derivative {
+        let x = x0.decompose();
         let f = -self.apply(&*x) / self.variance.value();
         *x * f
     }
 }
 
-
 // To calculate the the Lipschitz factors, we consider
 // f(t)    = e^{-t²/2}
 // f'(t)   = -t f(t)       which has max at t=1 by f''(t)=0
@@ -117,25 +110,26 @@
 // Hence the Lipschitz factor of ∇g is (C/σ²)f''(√3) = (C/σ²)2e^{-3/2}.
 
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<S, const N : usize> Lipschitz<L2> for Gaussian<S, N>
-where S : Constant {
+impl<S, const N: usize> Lipschitz<L2> for Gaussian<S, N>
+where
+    S: Constant,
+{
     type FloatType = S::Type;
-    fn lipschitz_factor(&self, L2 : L2) -> Option<Self::FloatType> {
-        Some((-0.5).exp() / (self.scale() * self.variance.value().sqrt()))
+    fn lipschitz_factor(&self, L2: L2) -> DynResult<Self::FloatType> {
+        Ok((-0.5).exp() / (self.scale() * self.variance.value().sqrt()))
     }
 }
 
-
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<'a, S : Constant, const N : usize> Lipschitz<L2>
-for Differential<'a, Loc<S::Type, N>, Gaussian<S, N>> {
+impl<'a, S: Constant, const N: usize> LipschitzDifferentiableImpl<Loc<N, S::Type>, L2>
+    for Gaussian<S, N>
+{
     type FloatType = S::Type;
-    
-    fn lipschitz_factor(&self, _l2 : L2) -> Option<S::Type> {
-        let g = self.base_fn();
-        let σ2 = g.variance.value();
-        let scale = g.scale();
-        Some(2.0*(-3.0/2.0).exp()/(σ2*scale))
+
+    fn diff_lipschitz_factor(&self, _l2: L2) -> DynResult<S::Type> {
+        let σ2 = self.variance.value();
+        let scale = self.scale();
+        Ok(2.0 * (-3.0 / 2.0).exp() / (σ2 * scale))
     }
 }
 
@@ -146,65 +140,73 @@
 // factors of the undifferentiated function, given how the latter is calculed above.
 
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<'b, S : Constant, const N : usize> NormBounded<L2>
-for Differential<'b, Loc<S::Type, N>, Gaussian<S, N>> {
+impl<'b, S: Constant, const N: usize> NormBounded<L2>
+    for Differential<'b, Loc<N, S::Type>, Gaussian<S, N>>
+{
     type FloatType = S::Type;
-    
-    fn norm_bound(&self, _l2 : L2) -> S::Type {
+
+    fn norm_bound(&self, _l2: L2) -> S::Type {
         self.base_fn().lipschitz_factor(L2).unwrap()
     }
 }
 
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<'b, 'a, S : Constant, const N : usize> NormBounded<L2>
-for Differential<'b, Loc<S::Type, N>, &'a Gaussian<S, N>> {
+impl<'b, 'a, S: Constant, const N: usize> NormBounded<L2>
+    for Differential<'b, Loc<N, S::Type>, &'a Gaussian<S, N>>
+{
     type FloatType = S::Type;
-    
-    fn norm_bound(&self, _l2 : L2) -> S::Type {
+
+    fn norm_bound(&self, _l2: L2) -> S::Type {
         self.base_fn().lipschitz_factor(L2).unwrap()
     }
 }
 
-
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<'a, S, const N : usize> Gaussian<S, N>
-where S : Constant {
-
+impl<'a, S, const N: usize> Gaussian<S, N>
+where
+    S: Constant,
+{
     /// Returns the (reciprocal) scaling constant $1/C=(2πσ^2)^{N/2}$.
     #[inline]
     pub fn scale(&self) -> S::Type {
         let π = S::Type::PI;
         let σ2 = self.variance.value();
-        (2.0*π*σ2).powi(N as i32).sqrt()
+        (2.0 * π * σ2).powi(N as i32).sqrt()
     }
 }
 
-impl<'a, S, const N : usize> Support<S::Type, N> for Gaussian<S, N>
-where S : Constant {
+impl<'a, S, const N: usize> Support<N, S::Type> for Gaussian<S, N>
+where
+    S: Constant,
+{
     #[inline]
-    fn support_hint(&self) -> Cube<S::Type,N> {
+    fn support_hint(&self) -> Cube<N, S::Type> {
         array_init(|| [S::Type::NEG_INFINITY, S::Type::INFINITY]).into()
     }
 
     #[inline]
-    fn in_support(&self, _x : &Loc<S::Type,N>) -> bool {
+    fn in_support(&self, _x: &Loc<N, S::Type>) -> bool {
         true
     }
 }
 
 #[replace_float_literals(S::Type::cast_from(literal))]
-impl<S, const N : usize> GlobalAnalysis<S::Type, Bounds<S::Type>>  for Gaussian<S, N>
-where S : Constant {
+impl<S, const N: usize> GlobalAnalysis<S::Type, Bounds<S::Type>> for Gaussian<S, N>
+where
+    S: Constant,
+{
     #[inline]
     fn global_analysis(&self) -> Bounds<S::Type> {
-        Bounds(0.0, 1.0/self.scale())
+        Bounds(0.0, 1.0 / self.scale())
     }
 }
 
-impl<S, const N : usize> LocalAnalysis<S::Type, Bounds<S::Type>, N>  for Gaussian<S, N>
-where S : Constant {
+impl<S, const N: usize> LocalAnalysis<S::Type, Bounds<S::Type>, N> for Gaussian<S, N>
+where
+    S: Constant,
+{
     #[inline]
-    fn local_analysis(&self, cube : &Cube<S::Type, N>) -> Bounds<S::Type> {
+    fn local_analysis(&self, cube: &Cube<N, S::Type>) -> Bounds<S::Type> {
         // The function is maximised/minimised where the 2-norm is minimised/maximised.
         let lower = self.apply(cube.maxnorm_point());
         let upper = self.apply(cube.minnorm_point());
@@ -213,68 +215,63 @@
 }
 
 #[replace_float_literals(C::Type::cast_from(literal))]
-impl<'a, C : Constant, const N : usize> Norm<C::Type, L1>
-for Gaussian<C, N> {
+impl<'a, C: Constant, const N: usize> Norm<L1, C::Type> for Gaussian<C, N> {
     #[inline]
-    fn norm(&self, _ : L1) -> C::Type {
+    fn norm(&self, _: L1) -> C::Type {
         1.0
     }
 }
 
 #[replace_float_literals(C::Type::cast_from(literal))]
-impl<'a, C : Constant, const N : usize> Norm<C::Type, Linfinity>
-for Gaussian<C, N> {
+impl<'a, C: Constant, const N: usize> Norm<Linfinity, C::Type> for Gaussian<C, N> {
     #[inline]
-    fn norm(&self, _ : Linfinity) -> C::Type {
+    fn norm(&self, _: Linfinity) -> C::Type {
         self.bounds().upper()
     }
 }
 
 #[replace_float_literals(C::Type::cast_from(literal))]
-impl<'a, C : Constant, const N : usize> Fourier<C::Type>
-for Gaussian<C, N> {
-    type Domain = Loc<C::Type, N>;
+impl<'a, C: Constant, const N: usize> Fourier<C::Type> for Gaussian<C, N> {
+    type Domain = Loc<N, C::Type>;
     type Transformed = Weighted<Gaussian<C::Type, N>, C::Type>;
 
     #[inline]
     fn fourier(&self) -> Self::Transformed {
         let π = C::Type::PI;
         let σ2 = self.variance.value();
-        let g = Gaussian { variance : 1.0 / (4.0*π*π*σ2) };
+        let g = Gaussian { variance: 1.0 / (4.0 * π * π * σ2) };
         g.weigh(g.scale())
     }
 }
 
 /// Representation of the “cut” gaussian $f χ\_{[-a, a]^n}$
 /// where $a>0$ and $f$ is a gaussian kernel on $ℝ^n$.
-pub type BasicCutGaussian<C, S, const N : usize> = SupportProductFirst<CubeIndicator<C, N>,
-                                                                       Gaussian<S, N>>;
-
+pub type BasicCutGaussian<C, S, const N: usize> =
+    SupportProductFirst<CubeIndicator<C, N>, Gaussian<S, N>>;
 
 /// This implements $g := χ\_{[-b, b]^n} \* (f χ\_{[-a, a]^n})$ where $a,b>0$ and $f$ is
 /// a gaussian kernel on $ℝ^n$. For an expression for $g$, see Lemma 3.9 in the manuscript.
 #[replace_float_literals(F::cast_from(literal))]
-impl<'a, F : Float, R, C, S, const N : usize> Mapping<Loc<F, N>>
-for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
-where R : Constant<Type=F>,
-      C : Constant<Type=F>,
-      S : Constant<Type=F> {
-
+impl<'a, F: Float, R, C, S, const N: usize> Mapping<Loc<N, F>>
+    for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
+where
+    R: Constant<Type = F>,
+    C: Constant<Type = F>,
+    S: Constant<Type = F>,
+{
     type Codomain = F;
 
     #[inline]
-    fn apply<I : Instance<Loc<F, N>>>(&self, y : I) -> F {
-        let Convolution(ref ind,
-                        SupportProductFirst(ref cut,
-                                            ref gaussian)) = self;
+    fn apply<I: Instance<Loc<N, F>>>(&self, y: I) -> F {
+        let Convolution(ref ind, SupportProductFirst(ref cut, ref gaussian)) = self;
         let a = cut.r.value();
         let b = ind.r.value();
         let σ = gaussian.variance.value().sqrt();
         let t = F::SQRT_2 * σ;
         let c = 0.5; // 1/(σ√(2π) * σ√(π/2) = 1/2
-        
+
         // This is just a product of one-dimensional versions
-        y.cow().product_map(|x| {
+        y.decompose().product_map(|x| {
             let c1 = -(a.min(b + x)); //(-a).max(-x-b);
             let c2 = a.min(b - x);
             if c1 >= c2 {
@@ -293,28 +290,27 @@
 /// and $f$ is a gaussian kernel on $ℝ^n$. For an expression for the value of $g$, from which the
 /// derivative readily arises (at points of differentiability), see Lemma 3.9 in the manuscript.
 #[replace_float_literals(F::cast_from(literal))]
-impl<'a, F : Float, R, C, S, const N : usize> DifferentiableImpl<Loc<F, N>>
-for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
-where R : Constant<Type=F>,
-      C : Constant<Type=F>,
-      S : Constant<Type=F> {
-
-    type Derivative = Loc<F, N>;
+impl<'a, F: Float, R, C, S, const N: usize> DifferentiableImpl<Loc<N, F>>
+    for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
+where
+    R: Constant<Type = F>,
+    C: Constant<Type = F>,
+    S: Constant<Type = F>,
+{
+    type Derivative = Loc<N, F>;
 
     /// Although implemented, this function is not differentiable.
     #[inline]
-    fn differential_impl<I : Instance<Loc<F, N>>>(&self, y0 : I) -> Loc<F, N> {
-        let Convolution(ref ind,
-                        SupportProductFirst(ref cut,
-                                            ref gaussian)) = self;
-        let y = y0.cow();
+    fn differential_impl<I: Instance<Loc<N, F>>>(&self, y0: I) -> Loc<N, F> {
+        let Convolution(ref ind, SupportProductFirst(ref cut, ref gaussian)) = self;
+        let y = y0.decompose();
         let a = cut.r.value();
         let b = ind.r.value();
         let σ = gaussian.variance.value().sqrt();
         let t = F::SQRT_2 * σ;
         let c = 0.5; // 1/(σ√(2π) * σ√(π/2) = 1/2
         let c_mul_erf_scale_div_t = c * F::FRAC_2_SQRT_PI / t;
-        
+
         // Calculate the values for all component functions of the
         // product. This is just the loop from apply above.
         let unscaled_vs = y.map(|x| {
@@ -340,12 +336,12 @@
                 // from the chain rule (the minus comes from inside c_1 or c_2, and changes the
                 // order of de2 and de1 in the final calculation).
                 let de1 = if b + x < a {
-                    (-((b+x)/t).powi(2)).exp()
+                    (-((b + x) / t).powi(2)).exp()
                 } else {
                     0.0
                 };
                 let de2 = if b - x < a {
-                    (-((b-x)/t).powi(2)).exp()
+                    (-((b - x) / t).powi(2)).exp()
                 } else {
                     0.0
                 };
@@ -355,16 +351,17 @@
     }
 }
 
-
 #[replace_float_literals(F::cast_from(literal))]
-impl<'a, F : Float, R, C, S, const N : usize> Lipschitz<L1>
-for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
-where R : Constant<Type=F>,
-      C : Constant<Type=F>,
-      S : Constant<Type=F> {
+impl<'a, F: Float, R, C, S, const N: usize> Lipschitz<L1>
+    for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
+where
+    R: Constant<Type = F>,
+    C: Constant<Type = F>,
+    S: Constant<Type = F>,
+{
     type FloatType = F;
 
-    fn lipschitz_factor(&self, L1 : L1) -> Option<F> {
+    fn lipschitz_factor(&self, L1: L1) -> DynResult<F> {
         // To get the product Lipschitz factor, we note that for any ψ_i, we have
         // ∏_{i=1}^N φ_i(x_i) - ∏_{i=1}^N φ_i(y_i)
         // = [φ_1(x_1)-φ_1(y_1)] ∏_{i=2}^N φ_i(x_i)
@@ -398,9 +395,7 @@
         // θ * ψ(x) = θ * ψ(y). If only y is in the range [-(a+b), a+b], we can replace
         // x by -(a+b) or (a+b), either of which is closer to y and still θ * ψ(x)=0.
         // Thus same calculations as above work for the Lipschitz factor.
-        let Convolution(ref ind,
-                        SupportProductFirst(ref cut,
-                                            ref gaussian)) = self;
+        let Convolution(ref ind, SupportProductFirst(ref cut, ref gaussian)) = self;
         let a = cut.r.value();
         let b = ind.r.value();
         let σ = gaussian.variance.value().sqrt();
@@ -408,7 +403,7 @@
         let t = F::SQRT_2 * σ;
         let l1d = F::SQRT_2 / (π.sqrt() * σ);
         let e0 = F::cast_from(erf((a.min(b) / t).as_()));
-        Some(l1d * e0.powi(N as i32-1))
+        Ok(l1d * e0.powi(N as i32 - 1))
     }
 }
 
@@ -426,39 +421,40 @@
 }
 */
 
-impl<F : Float, R, C, S, const N : usize>
-Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
-where R : Constant<Type=F>,
-      C : Constant<Type=F>,
-      S : Constant<Type=F> {
-
+impl<F: Float, R, C, S, const N: usize> Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
+where
+    R: Constant<Type = F>,
+    C: Constant<Type = F>,
+    S: Constant<Type = F>,
+{
     #[inline]
     fn get_r(&self) -> F {
-        let Convolution(ref ind,
-                        SupportProductFirst(ref cut, ..)) = self;
+        let Convolution(ref ind, SupportProductFirst(ref cut, ..)) = self;
         ind.r.value() + cut.r.value()
     }
 }
 
-impl<F : Float, R, C, S, const N : usize> Support<F, N>
-for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
-where R : Constant<Type=F>,
-      C : Constant<Type=F>,
-      S : Constant<Type=F> {
+impl<F: Float, R, C, S, const N: usize> Support<N, F>
+    for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
+where
+    R: Constant<Type = F>,
+    C: Constant<Type = F>,
+    S: Constant<Type = F>,
+{
     #[inline]
-    fn support_hint(&self) -> Cube<F, N> {
+    fn support_hint(&self) -> Cube<N, F> {
         let r = self.get_r();
         array_init(|| [-r, r]).into()
     }
 
     #[inline]
-    fn in_support(&self, y : &Loc<F, N>) -> bool {
+    fn in_support(&self, y: &Loc<N, F>) -> bool {
         let r = self.get_r();
         y.iter().all(|x| x.abs() <= r)
     }
 
     #[inline]
-    fn bisection_hint(&self, cube : &Cube<F, N>) -> [Option<F>; N] {
+    fn bisection_hint(&self, cube: &Cube<N, F>) -> [Option<F>; N] {
         let r = self.get_r();
         // From c1 = -a.min(b + x) and c2 = a.min(b - x) with c_1 < c_2,
         // solve bounds for x. that is 0 ≤ a.min(b + x) + a.min(b - x).
@@ -470,28 +466,31 @@
     }
 }
 
-impl<F : Float, R, C, S, const N : usize> GlobalAnalysis<F, Bounds<F>>
-for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
-where R : Constant<Type=F>,
-      C : Constant<Type=F>,
-      S : Constant<Type=F> {
+impl<F: Float, R, C, S, const N: usize> GlobalAnalysis<F, Bounds<F>>
+    for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
+where
+    R: Constant<Type = F>,
+    C: Constant<Type = F>,
+    S: Constant<Type = F>,
+{
     #[inline]
     fn global_analysis(&self) -> Bounds<F> {
         Bounds(F::ZERO, self.apply(Loc::ORIGIN))
     }
 }
 
-impl<F : Float, R, C, S, const N : usize> LocalAnalysis<F, Bounds<F>, N>
-for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
-where R : Constant<Type=F>,
-      C : Constant<Type=F>,
-      S : Constant<Type=F> {
+impl<F: Float, R, C, S, const N: usize> LocalAnalysis<F, Bounds<F>, N>
+    for Convolution<CubeIndicator<R, N>, BasicCutGaussian<C, S, N>>
+where
+    R: Constant<Type = F>,
+    C: Constant<Type = F>,
+    S: Constant<Type = F>,
+{
     #[inline]
-    fn local_analysis(&self, cube : &Cube<F, N>) -> Bounds<F> {
+    fn local_analysis(&self, cube: &Cube<N, F>) -> Bounds<F> {
         // The function is maximised/minimised where the absolute value is minimised/maximised.
         let lower = self.apply(cube.maxnorm_point());
         let upper = self.apply(cube.minnorm_point());
         Bounds(lower, upper)
     }
 }
-