# HG changeset patch
# User Tuomo Valkonen <tuomov@iki.fi>
# Date 1574093777 18000
# Node ID 5762e68842c9f159cb3301f25a80dc045ac8baa7
# Parent  888dfd34d24a8e59c2eae7b68efc28fc44b1ea50
Move Gradient to ImageTools

diff -r 888dfd34d24a -r 5762e68842c9 src/AlgTools.jl
--- a/src/AlgTools.jl	Mon Nov 18 11:00:54 2019 -0500
+++ b/src/AlgTools.jl	Mon Nov 18 11:16:17 2019 -0500
@@ -3,7 +3,6 @@
 include("LinkedLists.jl")
 include("StructTools.jl")
 include("Iterate.jl")
-include("Gradient.jl")
 include("Util.jl")
 
 end
diff -r 888dfd34d24a -r 5762e68842c9 src/Gradient.jl
--- a/src/Gradient.jl	Mon Nov 18 11:00:54 2019 -0500
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,185 +0,0 @@
-########################
-# Discretised gradients
-########################
-
-module Gradient
-
-##############
-# Our exports
-##############
-
-export ∇₂!, ∇₂ᵀ!, ∇₂fold!,
-       ∇₂_norm₂₂_est, ∇₂_norm₂₂_est²,
-       ∇₂_norm₂∞_est, ∇₂_norm₂∞_est²,
-       ∇₂c!,
-       ∇₃!, ∇₃ᵀ!,
-       vec∇₃!, vec∇₃ᵀ!
-
-##################
-# Helper routines
-##################
-
-@inline function imfold₂′!(f_aa!, f_a0!, f_ab!,
-                           f_0a!, f_00!, f_0b!,
-                           f_ba!, f_b0!, f_bb!,
-                           n, m, state)
-    # First row
-    state = f_aa!(state, (1, 1))
-    for j = 2:m-1
-        state = f_a0!(state, (1, j))
-    end
-    state = f_ab!(state, (1, m))
-
-    # Middle rows
-    for i=2:n-1
-        state = f_0a!(state, (i, 1))
-        for j = 2:m-1
-            state = f_00!(state, (i, j))
-        end
-        state = f_0b!(state, (i, m))
-    end
-
-    # Last row
-    state = f_ba!(state, (n, 1))
-    for  j =2:m-1
-        state = f_b0!(state, (n, j))
-    end
-    return f_bb!(state, (n, m))
-end
-
-#########################
-# 2D forward differences
-#########################
-
-∇₂_norm₂₂_est² = 8
-∇₂_norm₂₂_est = √∇₂_norm₂₂_est²
-∇₂_norm₂∞_est² = 2
-∇₂_norm₂∞_est = √∇₂_norm₂∞_est²
-
-function ∇₂!(u₁, u₂, u)
-    @. @views begin
-        u₁[1:(end-1), :] = u[2:end, :] - u[1:(end-1), :]
-        u₁[end, :, :] = 0
-
-        u₂[:, 1:(end-1)] = u[:, 2:end] - u[:, 1:(end-1)]
-        u₂[:, end] = 0
-    end
-    return u₁, u₂
-end
-
-function ∇₂!(v, u)
-    ∇₂!(@view(v[1, :, :]), @view(v[2, :, :]), u)
-end
-
-@inline function ∇₂fold!(f!::Function, u, state)
-    g! = (state, pt) -> begin
-        (i, j) = pt
-        g = @inbounds [u[i+1, j]-u[i, j], u[i, j+1]-u[i, j]]
-        return f!(g, state, pt)
-    end
-    gr! = (state, pt) -> begin
-        (i, j) = pt
-        g = @inbounds [u[i+1, j]-u[i, j], 0.0]
-        return f!(g, state, pt)
-    end
-    gb! = (state, pt) -> begin
-        (i, j) = pt
-        g = @inbounds [0.0, u[i, j+1]-u[i, j]]
-        return f!(g, state, pt)
-    end
-    g0! = (state, pt) -> begin
-        return f!([0.0, 0.0], state, pt)
-    end
-    return imfold₂′!(g!, g!, gr!,
-                     g!, g!, gr!,
-                     gb!, gb!, g0!,
-                     size(u, 1), size(u, 2), state)
-end
-
-function ∇₂ᵀ!(v, v₁, v₂)
-    @. @views begin
-        v[2:(end-1), :] = v₁[1:(end-2), :] - v₁[2:(end-1), :]
-        v[1, :] = -v₁[1, :]
-        v[end, :] = v₁[end-1, :]
-
-        v[:, 2:(end-1)] += v₂[:, 1:(end-2)] - v₂[:, 2:(end-1)]
-        v[:, 1] += -v₂[:, 1]
-        v[:, end] += v₂[:, end-1]
-    end
-    return v
-end
-
-function ∇₂ᵀ!(u, v)
-    ∇₂ᵀ!(u, @view(v[1, :, :]), @view(v[2, :, :]))
-end
-
-##################################################
-# 2D central differences (partial implementation)
-##################################################
-
-function ∇₂c!(v, u)
-    @. @views begin
-        v[1, 2:(end-1), :] = (u[3:end, :] - u[1:(end-2), :])/2
-        v[1, end, :] = (u[end, :] - u[end-1, :])/2
-        v[1, 1, :] = (u[2, :] - u[1, :])/2
-
-        v[2, :, 2:(end-1)] = (u[:, 3:end] - u[:, 1:(end-2)])/2
-        v[2, :, end] = (u[:, end] - u[:, end-1])/2
-        v[2, :, 1] = (u[:, 2] - u[:, 1])/2
-    end
-end
-
-#########################
-# 3D forward differences
-#########################
-
-function ∇₃!(u₁,u₂,u₃,u)
-    @. @views begin
-        u₁[1:(end-1), :, :] = u[2:end, :, :] - u[1:(end-1), :, :]
-        u₁[end, :, :] = 0
-
-        u₂[:, 1:(end-1), :] = u[:, 2:end, :] - u[:, 1:(end-1), :]
-        u₂[:, end, :] = 0
-
-        u₃[:, :, 1:(end-1)] = u[:, :, 2:end] - u[:, :, 1:(end-1)]
-        u₃[:, :, end] = 0
-    end
-    return u₁, u₂, u₃
-end
-
-function ∇₃ᵀ!(v,v₁,v₂,v₃)
-    @. @views begin
-        v[2:(end-1), :, :] = v₁[1:(end-2), :, :] - v₁[2:(end-1), :, :]
-        v[1, :, :] = -v₁[1, :, :]
-        v[end, :, :] = v₁[end-1, :, :]
-
-        v[:, 2:(end-1), :] += v₂[:, 1:(end-2), :] - v₂[:, 2:(end-1), :]
-        v[:, 1, :] += -v₂[:, 1, :]
-        v[:, end, :] += v₂[:, end-1, :]
-
-        v[:, :, 2:(end-1)] += v₃[:, :, 1:(end-2)] - v₃[:, :, 2:(end-1)]
-        v[:, :, 1] += -v₃[:, :, 1]
-        v[:, :, end] += v₃[:, :, end-1]
-    end
-    return v
-end
-
-###########################################
-# 3D forward differences for vector fields
-###########################################
-
-function vec∇₃!(u₁,u₂,u₃,u)
-    @. @views for j=1:size(u, 1)
-        ∇₃!(u₁[j, :, :, :],u₂[j, :, :, :],u₃[j, :, :, :],u[j, :, :, :])
-    end
-    return u₁, u₂, u₃
-end
-
-function vec∇₃ᵀ!(u,v₁,v₂,v₃)
-    @. @views for j=1:size(u, 1)
-        ∇₃ᵀ!(u[j, :, :, :],v₁[j, :, :, :],v₂[j, :, :, :],v₃[j, :, :, :])
-    end
-    return u
-end
-
-end # Module